CN111036846B

CN111036846B - Casting mould for producing a cast part having at least one inner contour

Info

Publication number: CN111036846B
Application number: CN201910966836.XA
Authority: CN
Inventors: U.拉布斯; J.绍尔瓦尔德
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2018-10-12
Filing date: 2019-10-12
Publication date: 2022-07-22
Anticipated expiration: 2039-10-12
Also published as: EP3636365B1; EP3636365A1; DE102018217546A1; CN111036846A

Abstract

The invention relates to a casting mould (100) for producing a casting having at least one inner contour, having a mould cavity (130) corresponding to the dimensions of the casting (200), and at least one core (140) arranged in the mould cavity (130) for forming an inner contour, wherein the core (140) is a component of a casting mould (100), the mold core (140) is designed in multiple parts and has a plurality of movable mold core segments (146) and mold cores (141) arranged between the mold core segments (146) in a longitudinally movable manner, wherein, when the mold core (141) is moved longitudinally, the mold core segment (146) is moved transversely to the direction of movement of the mold core (141) and can be moved out of the mold core (141) into a casting position and can be moved in of the mold core (141) into a demolding position.

Description

Casting mould for producing a cast part having at least one inner contour

Technical Field

The invention relates to a casting mold or casting die for producing a (metallic) casting having at least one inner contour.

Background

The casting mold is a permanent (reusable) casting mold of most metals for producing castings (casting elements). For this purpose, the casting mold has a mold cavity which can be filled with a melt or a liquid metal and forms a casting. The hollow or inner contour provided in the casting can be formed by means of a non-movable core and a movable loose piece. In order to be able to demould the produced cast part after solidification of the melt, the casting mold is constructed in multiple parts and is formed, for example, from fixed and movable mold halves. Furthermore, a so-called mold taper is required in order to be able to remove the cast part. This mold draft is also provided on the core (if a reusable permanent mold is involved) or on the loose piece. However, the mold draft causes oversize on the casting (German: Aufma. beta. en). This machining allowance must then be removed during the finishing of the casting (which is usually done by machining), which is complicated and results in a high material consumption. Furthermore, such machining allowances may also lead to excessively high wall thicknesses, thereby increasing the risk of defects, such as shrinkage cavities and bubbles, being generated.

DE 102015220980 a1 describes a casting mold for producing a metallic cast component having a multi-part loose piece. The flap is constructed in two pieces with a first partial flap and a second partial flap. The partial pieces can be moved in opposite oblique directions individually, i.e. separately from one another, during the retraction, so that no demolding inclination or mold inclination is required.

Disclosure of Invention

The invention now provides a further particularly advantageous casting mold having at least one core without the usual mold draft or demolding draft. Advantageous further developments of the casting mold according to the invention emerge from the following description and the drawing.

The casting mold or casting die according to the invention for producing a cast part having at least one inner contour comprises

A cavity corresponding to the dimensions of the casting (to be produced), and

at least one core arranged at least partially in the mold cavity or entering the mold cavity for forming the inner contour, wherein the core is not a disposable core but a (structural) component of the casting mold or a mold part.

According to the invention, the core is designed in multiple parts and has a plurality of movable core segments, i.e. at least two movable core segments, and a core arranged longitudinally displaceably between the core segments, wherein the core segments are moved or displaced transversely to the displacement direction of the core when the core is displaced longitudinally and can be brought into a casting position by the displacement of the core and into a demolding position by the displacement of the core.

The casting mold (casting mold) according to the invention is in particular a metal mold for the casting of metal molds or a diecasting mold or diecasting mold for diecasting metals, in particular light metals. The invention is also applicable to other metal casting processes using permanent molds.

The core and the core segment are components of the casting mold and form a permanent core. This is relatively easy to achieve, as the mould core can be moved in its longitudinal or axial direction and can be moved out and in by means of suitable drive means. During removal, the mold core is moved or pressed forward in the direction of the mold cavity. During the movement in, the mold core is moved back or pulled back in the opposite direction (i.e. outwards from the mold cavity). When the mold core is removed, the core segment is moved outward transversely, in particular substantially perpendicularly, to the direction of movement of the mold core and into the casting position. The core here is similar to the shape which is widened and forms the inner contour to be formed. When the mold core is moved in, the core segment is moved inward transversely to the direction of movement of the mold core and reaches a demolding position, or demolding position, in which the core is reduced or narrowed in cross section and demolding of the produced cast part is effected without mold draft or drawing draft. Only a small dimensional margin has to be trimmed for the inner contour, as a result of which, on the one hand, the trimming effort and material consumption are reduced and, on the other hand, the risk of defects is reduced.

The mould core is preferably arranged centrally and the mould core segments are arranged around said mould core. This achieves a compact core construction and ensures efficient functioning.

The mold core and the core segment may be configured with complementary ramps that constitute a wedge slide mechanism. Wedge-shaped slide mechanisms are known from various designs in the manufacture of moulds. The mold core may have, for example, a conical or frustoconical section on which a mold core section configured with corresponding complementary surfaces can slide and thus be displaced transversely to the direction of displacement of the mold core. The core section can be pretensioned against the mold core by means of a spring. The spring, in particular a compression spring (helical spring), ensures contact between the core segment and the mold core and also enables the core segment to be reset (returned) (into the demolding position). The resetting can also be effected hydraulically, pneumatically or mechanically (for example by means of an umbrella mechanism or other suitable hinge system or pin system).

The core segments are preferably guided in a displaceable manner by means of slotted guides or the like. The core segments can be supported in grooves provided for this purpose, for example, by means of one or more sliding blocks. The slotted guide may also be configured with an end stop that limits movement of the core segments.

The core section can have a mold element which forms the undercut inner contour. During casting, undercut portions can thus be produced on the inner contour of the cast part, which cannot be removed by conventional permanent cores or loose pieces.

Preferably, the casting to be produced has a hollow cylindrical region, the (cylindrical) inner contour of which is formed by a multi-part core (according to the invention), wherein the core has three (or more) movable core segments and the core structure has three (or more) recesses in which the core segments are arranged (in a laterally movable manner). The mold core preferably has three (or more) radially extending webs or radial webs which extend (in the longitudinal and radial direction) between the recesses, wherein the (radial) outer side faces of the radial webs together with the (radial) outer side faces of the mold core segments located in the casting position define or define the inner contour to be formed. The (radial) outer side of the radial webs is preferably designed with a pull-out slope, as a result of which the mold core can be moved in or back more easily.

The casting mold according to the invention is preferably used for producing stator cylinders for electrical machines, for which in particular aluminum alloys or magnesium alloys are used. However, the present invention is not limited thereto.

Drawings

The invention is explained in detail below by way of example and without limitation with reference to the figures. The features shown in the figures and/or described below, which are schematic and not to true scale, can also be a general feature of the invention, independently of the specific feature combination, and extend the invention accordingly.

Fig. 1 shows a cross-sectional view of a diecasting mold according to the invention with a multi-part core, the core segment of which is in its casting position,

figure 2 shows a cross-section of a core belonging to the die-casting mould of figure 1,

fig. 3 shows the die casting mould of fig. 1, wherein the core segment is now in its demoulding position,

fig. 4 shows a mold core belonging to the mold core of fig. 2 in a perspective view.

Detailed Description

The die casting mold 100 shown in fig. 1 has a lower, stationary mold half 110 and an upper, movable mold half 120. The lower mold half 110 is configured with a cavity 130 for making an annular cylindrical die cast component 200. The hollow-cylindrical inner contour is formed by a core 140, which will be explained in more detail below, and which core 140 is intended to keep the cavity free of melt during the injection molding process. That is, the mold cavity 130 is formed by an outer mold cavity wall of the lower mold half 110 and an inner mold cavity wall of the mold core 140, which together with the end mold cavity walls define the shape or shape of the injection molded part 200 to be produced. The upright orientation is merely exemplary. The mold halves 110, 120 can likewise be configured as a right-hand mold half and a left-hand mold half by being divided vertically.

The injection molding 200 is, for example, a thin-walled stator cylinder for accommodating a stator lamination stack in an electric machine for a vehicle drive (electric drive) of a motor vehicle. The die cast part 200 is, on the one hand, relatively thin-walled (for example less than 5mm) with respect to its diameter (for example greater than 200 mm). On the other hand, high mechanical requirements are placed on the die cast part 200. The mold inclination which should normally be provided on the outer and inner mold walls leads, as a function of the inclination angle, to a high and unequal wall thickness, whereby the risk of defects increases.

In the injection molding tool 100 according to the invention, the core 140 is of multi-part design and has a plurality of laterally displaceable core segments 146 and a core 141 arranged between the core segments 146 so as to be longitudinally or axially displaceable. The mold core 141 is constructed as shown in fig. 2 and 4 with three identically shaped recesses 145, in which recesses 145 identically shaped core segments 146 are arranged. The mold core 141 is also designed with a central conical or truncated cone 142 and three radial webs 143 projecting therefrom in the radial direction R, which radial webs 143 extend between the recesses 145 in a wing-like manner at an angular spacing of approximately 120 °. The mold core 141 is preferably manufactured in one piece as shown in fig. 4. The core section 146 bears on its radially inner side against the cone 142 in a form-fitting manner and is configured for this purpose with complementary conical sides.

When the mold core 141 is moved upward out of the mold core 141 as shown in fig. 1, the mold core segments 146 are moved radially outward transversely to the direction of movement of the mold core 141 by means of a wedge-shaped slider mechanism (the cones 142 act as wedge keys) (the movement distance and the transmission ratio can be adjusted by the inclination of the inclined surfaces sliding over one another) and into the casting position, wherein the radially outer side surfaces 144 of the radial webs 143 and the radially outer side surfaces 147 of the mold core segments 146 together define the cylindrical inner contour to be formed. Furthermore, the core segment 146 has on its outer side 147 a mold element 148 for forming an undercut geometry on the inner contour (see fig. 1). At least the undercut geometry, for example the internal annular groove for a fastening ring or the like, can thus be pre-cast.

After filling the mold cavity 130 with melt, the mold core 141 is moved in before the die casting part 200 reaches its demolding temperature (in order to reduce the shrinkage force), for which purpose the mold core 141 is moved or pulled back downward as shown in fig. 3. The core segments 146 are moved radially inward transversely to the direction of movement of the mold core 141 and reach their demolding position, wherein a circumferential gap S is formed between the radially outer side 147 and the inner contour of the die casting 200 (i.e. the mold core 200 no longer contacts the die casting 200), which allows easy removal of the die casting 200 (die casting 200 is demolded upward). The outer side 144 of the radial webs 143 is preferably formed with a draft angle (e.g., 1 ° to 3 °) over the entire length of the outer side 144, so that the outer side 144 can be removed from the die casting part 200 when the die core 141 is retracted (the outer side 147 of the die core section 146 is not formed with a die draft or a draft angle). A conventional mold taper may be present on the cavity wall on the outside of the lower mold half 110. The lower mold half 110 may also be configured in a vertical split for demolding, thereby eliminating the need for mold draft at all. This enables die casting of an annular cylindrical die cast part 200 having a uniform thin wall thickness and having only a small machining margin (for example, less than 1.5 mm).

As described above, by removing the mold core 141, the core segment 146 is moved transversely to the movement axis L of the mold core 141 and into the casting position, as is indicated by the arrow in fig. 1. The core segment 146 is brought or returned into the demolding position by moving into the mold core 141, as is indicated by the arrow in fig. 3. The core segment 146 here moves only in the radial direction R (in contrast to a loose piece which moves forward and backward by moving in and out). The radial displacement guidance of the core segments 146 is effected both by the radial webs 143 and by means of groove guides. The lower mold half 110 is formed for this purpose with a groove 119 or the like, in which the core segment 146 is mounted so as to be movable in the radial direction R by means of a slide 149 or the like and is held in the circumferential direction as well as in the axial direction and is secured against twisting and tilting. The slide 149 may be screwed onto the core segment 146 or may be integrally formed with the core segment 146. A spring 150 is also arranged in the groove 119, which pretensions the core segment 146 against the mold core 141 and effects a return.

List of reference numerals

100 mould

110 mold half

119 groove

120 mold half

130 type cavity

140 type core

141 mould core

142 vertebral body

143 radial spacer

144 (on radial spacers) outer side

145 concave part

146 core segment

147 (on the core section)

148 mould element

149 slide block

150 spring

200 casting

L longitudinal direction

R radial direction

S gap

Claims

1. A casting mold (100) for producing a cast part (200) having at least one inner contour has

-a cavity (130) conforming to the dimensions of the casting (200), and

-at least one core (140) arranged in the mould cavity (130) for forming an inner contour, wherein the core (140) is a component of the casting mould (100),

wherein the mold core (140) is designed in multiple parts and has a plurality of movable mold core segments (146) and mold cores (141) arranged between the mold core segments (146) in a longitudinally movable manner, wherein, when the mold cores (141) are moved longitudinally, the mold core segments (146) are moved transversely to the direction of movement of the mold cores (141) and can be moved out of the mold cores (141) into a casting position and can be moved in by the mold cores (141) into a demolding position,

it is characterized in that the preparation method is characterized in that,

the casting (200) to be produced has a hollow-cylindrical region, the inner contour of which is formed by a multi-part core (140), the core (141) being arranged centrally and the core segments (146) being arranged around the core (141),

wherein the core (140) has three or more movable core segments (146) and the core (141) is configured with three or more recesses (145) in which the core segments (146) are arranged laterally movably,

wherein the casting mold (100) has a lower, stationary mold half (110), the mold cavity (130) being formed by a mold cavity wall on the outer side of the lower mold half (110) and a mold cavity wall on the inside of the core (140),

the core segment (146) is guided in a moving manner by means of a groove (119) formed in the lower mold half (110) and a slide (149) screwed to the core segment (146) or formed integrally with the core segment (146), the outer side (147) of the core segment (146) not being formed with a pull-out slope.

2. The casting mold (100) according to claim 1, characterized in that the mold core (141) has three radial webs (143) which extend between the recesses (145), wherein outer side faces (144) of the radial webs (143) together with outer side faces (147) of the core segments (146) in the casting position define an inner contour to be formed.

3. A casting mold (100) according to claim 2, characterized in that the outer side (144) of the radial spacers (143) are configured with a drawing slope.

4. A mould (100) according to any one of the preceding claims, wherein the core (141) and core segment (146) are configured with complementary ramps, which constitute a wedge slide mechanism.

5. The casting mold (100) according to claim 4, characterized in that the core section (146) is pretensioned against the mold core (141) by means of a spring (150).

6. A casting mould (100) according to one of the claims 1 to 3, characterized in that the core section (146) is configured with mould elements (148) which realize the formation of an undercut inner contour.

7. Use of a casting mould (100) according to one of the preceding claims for manufacturing a stator cylinder for an electrical machine.