EP1802411B1 - Casting die and method for producing cast workpieces consisting of light metal alloys - Google Patents

Abstract

The invention relates to a casting tool for producing workpieces from light metal alloys. The system includes a positioning element, a core part, a first mold part structured to carry the positioning element and be movable toward the core part, and a core part support structured to support the core part. The system also includes at least one stop structured to limit movement of the front mold part toward the core part and to allow the positioning element to be introduced into the core part, whereby the positioning element holds the core part in a predetermined position for casting.

Description

The invention relates to a casting tool for producing workpieces cast from light metal alloys, in particular for the motor vehicle industry, wherein at least one positioning element is provided for fixing at least one preformed core part remaining in the cast workpiece in a predetermined position in the casting tool, the casting tool being at least two relative to one another having movable mold parts and at least one tapered to its free end pin-shaped positioning is mounted in a movably mounted mold part and a method for producing light alloy castings workpieces, especially for the automotive industry, wherein at least one preformed in the cast workpiece remaining core part in a predetermined position is held in a casting tool, wherein the core part is frictionally held by the positioning during casting.

In the manufacture of workpieces made of light metal alloys, it is already known to hold preformed core parts by means of positioning elements in the casting tool, so that the core parts can be encapsulated by the light metal alloy melt.

In the US Pat. No. 5,992,500 the casting of a metal foam consisting of the core part is shown, wherein the core part by means of tapering to their free ends pin-shaped positioning is held without contact of the moldings. In addition, although the casting tool on two mold parts, which are movable relative to each other and to which the pin-shaped positioning elements are attached. However, it does not disclose how to attach the core member between the pin-shaped members.

A similar casting process is also already from the WO1 / 66283 A1 or the AT 409 728 B in which, however, in the core part fixedly arranged positioning elements are provided. These positioning elements also have an air discharge channel for the escape of expanding air. However, such positioning elements arranged in the core part have a relatively large circumference and form material weak points, so that very high stress peaks occur in these areas when the rim is loaded, in particular in the case of dynamic bending and torsional stresses.

From the EP 0 922 591 A For example, a rim made of a light metal alloy is known, in which a core part has fixed positioning elements to be positioned in the mold. However, this method also has a very high outlay on production technology, and equally high voltage peaks occur due to the positioning elements fixedly arranged in the core part.

From the US 2004/0099398 A1 For example, a positioning element for a sand core is known, wherein the positioning element is attached in the manufacture of the sand core in this, and via which a connection can be made with the casting tool.

In the DE 42 01 278 A1 props or positioning elements for stabilizing casting cores in the production of moldings are described. Here, the pin-shaped positioning, which are fastened in the manner of a nail in the casting tool, a transversely extending to the longitudinal direction of the shaft of the positioning element Eingießelement which is solidly fused to the fixed connection of the positioning in the molded body to be cast in the molding.

Furthermore, it is also known to form in the production of cast workpieces cavities by means of core parts, which are removed from the cast workpiece again, such as sand cores. However, comparatively large openings are required for removal, which in turn causes high voltage peaks in the region of these openings.

From the EP 1 116 536 A For example, a casting method is known which relates to a quench-casting process for producing a cast aluminum product, thereby casting a pipe. To fix the tube in the mold pin-shaped positioning are retracted into the tube ends.

From the JP 01 241369 a method for casting over a workpiece is known in which it is held between two mold parts of a casting mold by means of a pin-shaped positioning element.

In the US Pat. No. 5,392,841 a sand core is shown, which is mounted on pin-shaped Positionierelemeten.

In the JP 01 138050 A a different casting method for the production of a watch case is shown. Here is a after the completion of the watch case removable casting core positioned on a pin-shaped positioning.

In the JP 56 011 4050 A a casting tool is shown, in which a molded part has a pin-shaped positioning element, which penetrates into the core part for fixing. Here, the core part is held during the casting between the moldings.

It is an object of the present invention to provide a casting tool and a method for producing workpieces cast from light metal alloys, in which high voltage peaks due to the positioning elements are avoided. In addition, an exact positioning of the core parts should be ensured and a relatively high degree of design freedom in the production of workpieces are made possible.

This is achieved in the casting tool of the type mentioned in that a provided for supporting the core part movable core member pad is provided which is removable from the casting tool, wherein the positioning member carrying the molding of the casting tool on the resting on the core member pad core part is moved up to a stop on the core part, so that the positioning element is inserted into the resting on the core part pad core part and the core part is held after removal of the core part pad during casting over the positioning in a predetermined position and after completion of the Workpiece the positioning is pulled out of this. With the aid of free-projecting pin-shaped positioning elements fastened to the casting tool, the core part (s) of the light metal workpiece to be produced can be reliably held in a predetermined position in the casting tool, but only relatively small openings or impressions in the core part or impressions after removal of the positioning elements the light metal surrounding the core part remain at the point at which a positioning element has penetrated into the core part during the casting process, so that the finished light metal workpiece has only comparatively lower stress peaks in the region of the positioning elements. With the help of relative mutually movable mold parts, wherein the pin-shaped positioning is mounted in a movably mounted molding, the casting tool can be closed in a simple manner and the core part by means of the pin-shaped positioning in a predetermined position in the casting tool to be fixed. In principle, with the casting tool any workpieces of light metal alloys, in particular of aluminum-containing light metal alloys, are produced, in particular in the field of motor vehicle industry a great need for light metal workpieces is given, so that with the casting tool in particular light metal wheels or rims and longitudinal and wishbones, subframe parts, various types of struts and components for suspensions and the like can be made. Due to the low stress peaks, which can be achieved with the help of the pin-shaped positioning elements attached to the casting tool, the workpieces produced by means of the casting tool according to the invention are particularly well suited to be exposed to dynamic bending and torsional forces. For "skewering" the core part, it is advantageous if the upper mold part is arranged to be movable.

When the core member pad is retractable in the fixed lower mold part, after the core member has been attached to the positioning member, the core pad can be easily removed from the mold.

In order to prevent the positioning elements from penetrating into the core part beyond a predetermined penetration depth, it is advantageous if a movable core part support is provided with at least one stop limiting the downward stroke of the movable molding.

If the core part pad is resiliently mounted on a support, any inequalities can be compensated when driving down the upper molding advantageously.

In order to achieve a self-centering of the core part pad and thus to ensure an exact positioning of the core part in the casting tool, so that the positioning reliably penetrate the desired location in the core part, it is advantageous if the carrier of the core part pad by means of centering in guides a molding is slidably mounted.

To the penetration of the positioning in the core part facilitate, it is advantageous if the pin-shaped positioning element is at least partially conical.

In particular, it is advantageous if the pin-shaped positioning has a conical tip portion, as thus the core part can be easily impaled and at the same time the smallest possible impression in the core after removal of the positioning remains, which in turn low the voltage spikes in the finished light metal workpiece can be kept.

Tests have shown that the positioning element penetrates easily into the core part and at the same time a reliable frictional engagement between the pin-shaped positioning and the core part is achieved when the conical tip portion has an opening angle between 10 ° and 30 °, in particular of substantially 20 ° , having.

In order to reliably hold the core parts by means of a frictional connection to the positioning elements, it is advantageous if a cylindrical section adjoins the conical end section.

Tests have further shown that the core part is held reliably in its predetermined position in the casting tool and at the same time a relatively small impression remains in the core part or the light metal alloy enclosing the core part after the removal of the positioning element, if the cylindrical section has a diameter smaller than 3 mm, preferably less than 2 mm, in particular of substantially 1.6 mm.

In order to remove pin-shaped positioning easily from the finished light metal workpiece, it is advantageous if a conical section adjoins the cylindrical portion.

Tests have shown that it is particularly favorable in this context if the conical section has an opening angle between 5 ° and 15 °, in particular of substantially 10 °.

In order to fasten the pin-shaped positioning element to the casting tool in a simple manner, it is advantageous if the pin-shaped positioning element has a fixing section which is larger than the cylindrical or conical section.

When the attachment portion in the attached state of Positioning element is received in a recess in the casting tool, protrude only a comparatively small circumference having portions of the positioning in the core part or in the light metal alloy surrounding the core part.

In order to be able to easily insert the attachment portion into the recess of the casting tool or to achieve a frictional attachment of the attachment portion in the recess of the casting tool, it is favorable if the attachment portion to the opposite end of the front tip portion of the pin-shaped positioning slightly conically tapered.

In order reliably to fix the pin-shaped positioning element in the casting tool, it is advantageous if the positioning element is fastened in a frictional engagement or via an adhesive connection in a recess of the casting tool. Instead of the frictional or adhesive connection can of course also be provided a screw, soldered or welded connection or a form-fitting connection for attachment of the positioning element in the casting mold.

The method of the initially mentioned type is characterized in that a movable, the positioning member-carrying molded part of the casting tool is moved toward the resting on a core part pad core part for frictional connection between the core part and the positioning to a stop on the core part, so that the positioning member attached to the casting tool is inserted into the core member before the core member liner is removed from the casting tool, and the core member is held in a predetermined position via the positioning member after removal of the core member liner during casting, and after completion of the workpiece the positioning is pulled out of this.

If the core part has a lower density than the light metal alloy, a comparatively light cast work piece can be produced in a simple manner compared to a workpiece cast integrally from the light metal alloy. The core part may in this case in particular of metal foam, for example of aluminum foam, or from a compact of porous silicate material, such as vermiculite, or like exist.

In order to increase the strength of the workpiece cast from the light metal alloy, it is advantageous if the core part has a higher density than the light metal alloy. The core part may in this case consist in particular of steel or the like.

The invention will be explained in more detail with reference to a preferred embodiment shown in the drawing, to which, however, it should not be limited.

• Fig. 1 einen Querschnitt eines Teils eines Gießwerkzeuges mit einem darin eingebrachten Kernteil;
• Fig. 2 eine Detailansicht eines stiftförmigen Positionierelements;
• Fig. 3 eine schematische Ansicht eines Gießwerkzeugs für die Herstellung eines Leichtmetallwerkstücks unter Einlegen eines Kernteils, der auf einer Kernteilunterlage aufliegt.

In detail, in the drawing:

• Fig. 1 a cross section of a part of a casting tool with a core part introduced therein;
• Fig. 2 a detailed view of a pin-shaped positioning element;
• Fig. 3 a schematic view of a casting tool for the production of a light metal workpiece with insertion of a core member which rests on a core part pad.

In Fig. 1 partially a casting tool 1 for producing a light metal rim 2 can be seen, in which a core part 3 is provided which has a lower density than the light metal alloy, which is encapsulated by the light metal alloy. For example, the core part 3 could consist of metal foam, in particular of aluminum foam, or also of a pressed body of porous silicate material, eg vermiculite, or else of a steel ring or the like.

The casting tool 1 is essentially composed of a movable mold upper part 4 and a fixed mold bottom part 5 and lateral core slides 6. As a core slide 6, for example, four quarter-circular individual parts may be present, which are displaced from the outside radially inwardly to bear against the lower part of the mold 5 when closing the casting tool 1.

The Kokillenoberteil 4 has a recess 4 ', in which a pin-shaped positioning element 7, which preferably consists of steel, is fixed by means of an adhesive bond. With the aid of the pin-shaped positioning element 7, the core part 3 is held in a predetermined position in the casting tool 1 so that the core part 3 can be encapsulated by the light metal alloy when the liquid light metal alloy penetrates into the casting tool. After finishing the casting process the movably mounted upper mold part 4 is again moved upwards and thus the pin-shaped positioning element 7 is pulled out of the core part 3 or the light metal alloy surrounding the core part. Due to the relatively small diameter of the pin-shaped positioning 7 thus remains only a relatively small opening in the light metal alloy 2 and the core part 3, so that compared to known in the core part 3 fixed positioning positioning significantly lower stress peaks occur in the finished workpiece under stress.

In Fig. 2 the pin-shaped positioning element 7 is shown in detail. It can be seen in particular that a conical tip section 8 is provided for easy penetration into the core part 3. In the embodiment shown, an opening angle α of approximately 20 ° is provided.

At the tip portion 8 then includes a cylindrical portion 9, which, as in Fig. 1 can be seen in the penetrated into the core part 3 position is also included in the interior of the core part 3. In order to keep the voltage peaks in the light metal workpiece as small as possible after removal of the positioning element, the cylindrical section 9 has the smallest possible diameter, with a diameter of approximately 1.6 mm being provided in the exemplary embodiment shown.

The cylindrical section 9 is adjoined by a conical section 10 with an opening angle β of approximately 10 °. This conical section 10 is during the casting of the light metal workpiece, as in Fig. 1 visible, surrounded by the light metal alloy and removed after completion of the workpiece from this.

To the conical section 10 includes a step-shaped diameter extension to a mounting portion 11, which is provided for receiving in a recess 6 of the casting mold 1. In order to achieve a simple introduction into the recess 6 and a certain frictional engagement between the attachment portion 11 and the recess 6, the attachment portion 11 is slightly conical. An end section 12 then adjoins the attachment section 11, which has a smaller diameter relative to the attachment section 11, so that an adhesive is reliably between the end portion 12 and the recess 6 of the casting tool 1 can penetrate.

In Fig. 3 is a schematic view of the casting tool 1 is shown, in particular, a vertically displaceable in the direction of arrow 13 support 14 can be seen, which is mounted in the Kokillenunterteil 5 retractable. On the carrier 14, a plate-shaped core part pad 15 is resiliently mounted to compensate for any inequalities when driving down the Kokillenoberteils 4. At the core part pad 15 columnar stops 16 are provided which serve to accommodate the desired distance to the mold upper part 4, which is pushed by means of a support plate 17 down when receiving the core part 3. In the design of the height of the stops 16, a measure is set, so that the pin-shaped positioning 7 (as in Fig. 1 shown) reliably penetrate into the core part 3, ie, the core part 3 "skewer" to keep the core part 3 in a predetermined position in the closed casting tool 1 after lowering the carrier 4 and the core part pad 15.

In a flanged to the mold top 4 end portion 18 ejector pins 19 are provided in a conventional manner, which are provided for separating the light metal workpiece from Kokillenoberteil 4.

Thus, in the preferred embodiment, reference has been made to the manufacture of a light metal rim. Of course, however, the casting tool according to the invention can also be used for the production of any other light metal workpieces with remaining in the cast workpiece core parts, for example for the production of suspensions, longitudinal and wishbones, subframe parts, various types of struts and the like.

Claims (20)

1. A casting tool (1) for the production of workpieces (2) cast from light-metal alloys, in particular for the motor vehicle industry, wherein at least one positioning element (7) is provided for fixing in a predetermined position within the casting tool (1) at least one preformed core part (3) remaining in the cast workpiece (2), wherein the casting tool (1) has at least two mold parts (4, 5) movable relative to each other, and at least one pin-shaped positioning element (7) which tapers towards its free end is fastened in a movably mounted mold part (4), characterized in that a movable core part support (15) arranged for resting on the core part (3) is provided, said support being removable from the casting tool (1), wherein the mold part (4), which carries the positioning element (7), of the casting tool (1) is movable up to a stop (16) towards the core part (3) resting on the core part support (15) in a manner that the positioning element (7) is introduceable in to the core part (3) resting on the core part support (15) and the core part (3), after removal of the core part support (15), is held in a predetermined position over the positioning element (7) during casting and the positioning element (7) is removed from the workpiece (2) upon completion of the same.
2. A casting tool according to claim 1, characterized in that the upper mold part (4) is arranged to be movable.
3. A casting tool according to claim 1 or 2, characterized in that core part support (15) is immersibly arranged in the fixedly arranged, lower mold part (5).
4. A casting tool according to claim 2 or 3, characterized in that a movable core part support (15) which includes at least one stop (16) that limits the downward travel of the movable mold part (4) is provided.
5. A casting tool according to any one of claims 1 to 4, characterized in that the core part support (15) is resiliently mounted on a carrier (14).
6. A casting tool according to claim 5, characterized in that the carrier (14) of the core part support (15) is displaceably mounted in guides of a mold part (4, 5) by means of centering pins.
7. A casting tool according to claim 1 bis 6, characterized in that the pin-shaped positioning element (7) is designed to be at least partially conical.
8. A casting tool according to any one of claims 1 to 7, characterized in that the pin-shaped positioning element (7) comprises a conical tip portion (8).
9. A casting tool according to claim 8, characterized in that the conical tip portion (8) has an opening angle (α) of between 10° and 30° and, in particular, substantially 20°.
10. A casting tool according to claim 8 or 9, characterized in that a cylindrical subportion (9) follows upon the conical tip portion (8).
11. A casting tool according to claim 10, characterized in that the cylindrical subportion (9) has a diameter smaller than 3mm, preferably smaller than 2mm and, in particular, of substantially 1.6mm .
12. A casting tool according to claim 10 or 11, characterized in that a conical subportion (10) follows upon the cylindrical subportion (9).
13. A casting tool according to claim 12, characterized in that the conical subportion (10) has an opening angle (β) of between 5° and 15° and, in particular, substantially 10°.
14. A casting tool according to any one of claims 10 to 13, characterized in that the pin-shaped positioning element (7) comprises a fastening portion (11) having a larger periphery than the cylindrical and/or conical subportion (9, 10).
15. A casting tool according to claim 14, characterized in that the fastening portion (11), in the fastened state of the positioning element (7), is received in a recess (4') within the casting tool (1).
16. A casting tool according to claim 14 or 15, characterized in that the fastening portion (11) tapers slightly conically to the end of the pin-shaped positioning element (7), located opposite the front tip portion (8).
17. A casting tool according to any one of claims 1 to 16, characterized in that the positioning element (7) is fixed in a recess (4') of the casting tool (1) in a frictionally engaged manner or via an adhesive connection.
18. A method for producing workpieces (2) cast from light-metal alloys, in particular for the motor vehicle industry, wherein at least one preformed core part (3) remaining in the cast workpiece (2) is held in a predetermined position within a casting tool (1), wherein the core part (3) of the positioning element (7) is held frictionally during casting, characterized in that a movable mold part (4), which carries the positioning element (7), of the casting tool (1) is moved up to a stop (16) towards the core part (3), which rests on a core part support (15), for frictional engagement between the core part (3) and the positioning element (7) in a manner that the positioning element (7) fastened to the casting tool (1) is introduced into the core part (3) before the core part support (15) is removed from the casting tool (1), and the core part (3), after removal of the core part support (15), is held in a predetermined position over the positioning element (7) during casting, and that the positioning element (7) is removed from the workpiece (2) upon completion of the same.
19. A method according to claim 18, characterized in that the core part (3) has a lower density than the light-metal alloy.
20. A method according to claim 18, characterized in that the core part (3) has a higher density than the light-metal alloy.

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