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EP-4549050-B1 - DIE-CASTING TOOL AND DIE-CASTING METHOD FOR PRODUCING A RAW CAST WHEEL

EP4549050B1EP 4549050 B1EP4549050 B1EP 4549050B1EP-4549050-B1

Inventors

  • HUMMEL, MARC

Dates

Publication Date
20260513
Application Date
20241025

Claims (10)

  1. Pressure die-casting tool for producing a raw cast wheel (1) in which a mold is filled by means of a central sprue in a filling direction from a wheel hub (3) via spokes (7) radially outwards to a front flange (9) and from there axially via a rim base (11) to a rear flange (13), wherein in order to avoid solidification cavities the pressure die-casting tool has in the region of the rear flange (13) a number of booster compressors (37, 39) which are distributed in the circumferential wheel direction and which during the casting process compress the casting material (42) in the region of the rear flange (13), and in that the number of booster compressors has a group of radial booster compressors (39) and a group of axial booster compressors (37).
  2. Pressure die-casting tool according to claim 1, characterized in that each of the booster compressors (37, 39) is a booster compressor piston and in that the booster compressor piston (37, 39) during a booster compression phase which takes place in the casting process moves into a compression space (41, 43) of a rear flange part-cavity of the pressure die-casting tool with local pressure build-up in the melt (42) which is located in the rear flange part-cavity.
  3. Pressure die-casting tool according to claim 2, characterized in that the group of radial booster compressors (39) is arranged radially outside the rear flange part-cavity of the pressure die-casting tool, and in that the radial booster compressors (39) act with a radial booster compressor piston stroke on the rear flange part-cavity, and in that the group of axial booster compressors (37) is arranged axially beside the rear flange part-cavity of the pressure die-casting tool, that is to say at right-angles with respect to the radial booster compressors (37), and in that the axial booster compressors (39) act with an axial booster compressor piston stroke on the rear flange part-cavity of the pressure die-casting tool.
  4. Pressure die-casting tool according to claim 3, characterized in that the axial booster compressors (37) and the radial booster compressors (39) are arranged in series alternating one behind the other in the circumferential wheel direction and are offset from each other by means of division spacings so that at least one booster compressor (39) of the second group is arranged centrally between two adjacent booster compressors (37) of the first group.
  5. Pressure die-casting tool according to claim 4 or 5, characterized in that the rear flange (13) forms with its outer flank (15) a wheel rear side and defines with its inner flank (14), together with the rim base (11) an inner corner region, and in that the radial booster compressor (39) acts on the inner corner region between the rear flange inner flank (17) and rim base (11), and in that the axial booster compressor (37) acts on the rear flange outer flank (15).
  6. Pressure die-casting tool according to any one of the preceding claims, characterized in that the casting process has a mold filling phase in which a casting piston (31) in the sprue region of the pressure die-casting tool can be adjusted by a filling stroke in order to fill the cavity (20) of the pressure die-casting tool completely with liquid casting material (42), and in that the casting process has a holding pressure phase in which the casting piston (31) is adjusted by a holding pressure stroke in order to compact the casting material which is located in the cavity and which has not yet solidified, and in that the redensification phase is carried out at the same time as the holding pressure phase or with a time delay with respect to the holding pressure phase.
  7. Pressure die-casting tool according to any one of the preceding claims, characterized in that the pressure die-casting tool is a three-plate pressure die-casting tool which is formed from a fixed mold half (21) and a movable mold half (23) and a floating mold half (25) which is arranged therebetween, and in that the fixed mold half (21) and the floating mold half (25) form a sprue region via which the liquid casting material (42) is poured into the cavity (20), and in that the cavity (20) is formed between the floating mold half (25) and the movable mold half (23).
  8. Pressure die-casting tool according to claim 7, characterized in that the movable mold half (23) is sub-divided into a base body (33) which has a rotationally symmetrical, radially inner mold face which delimits the cavity (20) internally, and in particular four radially outer sliding members (35) which together form a rotationally symmetrical, radially outer mold face which delimits the cavity (20) externally.
  9. Pressure die-casting tool according to claim 8, characterized in that the radial booster compressors (39) are guided so as to be able to be adjusted in terms of stroke in the radially outer sliding members (35), in particular two radial booster compressors (39) per sliding member (35), and/or in that the axial booster compressors (37) are guided so as to be able to be adjusted in terms of stroke in the base body (33) of the movable mold half (23).
  10. Method for producing a raw cast wheel (1) in a pressure die-casting tool according to any one of the preceding claims, in which a mold is filled by means of a central sprue in a filling direction from a wheel hub (3) via spokes (7) radially outwards to a front flange (9) and from there axially via a rim base (11) to a rear flange (13), wherein in order to avoid solidification cavities the pressure die-casting tool has in the region of the rear flange (13) a number of booster compressors (37, 39) which are distributed in the circumferential wheel direction and which during the casting process compress the casting material (42) in the region of the rear flange (13), and in that the number of booster compressors has a group of radial booster compressors (39) and a group of axial booster compressors (37).

Description

The invention relates to a die-casting tool according to the preamble of claim 1 and a die-casting method according to the preamble of claim 10. A raw cast wheel can be manufactured using a die-casting process. After production, the raw cast wheel is further processed into a vehicle wheel. In the die-casting process, the mold is filled via a central sprue, with the molten metal flowing radially outwards from the wheel hub, through the spokes, to a front rim, and then axially across a rim well to a rear rim. The advantage of die-casting lies in the ability to cast thin walls with very close contours. This minimizes material usage, conserves resources, and reduces manufacturing effort by requiring less machining of the raw cast wheel. Ideally, in die-casting, the molten metal should flow from thicker to thinner wall thicknesses. In this case, the molten metal accelerates progressively, thus preventing casting defects such as pre-solidification, solidification shrinkage cavities, and porosity. The following problem arises during the die casting of a raw cast wheel: During the filling process, the flow front moves from the thin-walled rim bed to the thick-walled rear horn. With this flow direction from the thin-walled rim bed to the thick-walled rear horn, solidification cavities form in the rear horn. A holding pressure phase carried out during the casting process cannot have an effect in the thick-walled rear horn, as the molten metal in the area of the thin-walled rim bed has already solidified and therefore cannot act on it. Compaction in the area of the rear horn is no longer possible. For this reason, it is not possible with current technology to produce a porosity-free vehicle wheel in the area of the rear horn. From the DE 10 2020 100 702 A1 A generic method for manufacturing an aluminum rim for a motor vehicle wheel is known. From the DE 10 2016 104 019 B3 A device for manufacturing a casting, in particular a wheel rim, by means of a die-casting process is known. The device has a lower base plate, an upper vertically movable plate, and four horizontally movable side parts or side slides. From the DE 10 2017 125 634 A1 A casting device for manufacturing a light alloy wheel is known. The casting device comprises a base plate, a punch, and side slides. During the casting process, post-compaction occurs via the punch to prevent voids. From the US 2016 368 043 A1 A device for die-casting a wheel is known. The device comprises a tool with a lower part, an upper part, and four side parts. The object of the invention is to provide a die-casting tool and a die-casting process for producing a raw cast wheel in which, compared to the prior art, solidification cavities in the raw cast wheel can be avoided in a simple manner. The problem is solved by the features of claim 1 or 10. Preferred embodiments of the invention are disclosed in the dependent claims. The invention relates to a die-casting tool for producing a raw cast wheel. In the die-casting process, the mold is filled via a central sprue with a filling direction from a wheel hub, radially outwards through spokes to a front rim, and from there axially via a rim bed to a rear rim. According to the characterizing part of claim 1, solidification cavities in the raw cast wheel are avoided as follows: The die-casting tool has a number of [missing information] in the area of the rear rim. The casting process involves secondary compactors distributed along the wheel's circumference. These compactors can locally compress the casting material in the area of the rear horn during the casting process. This local compression displaces the still-soft casting material in the rear horn cavity along a flow path in the wheel's circumference. As a result, the casting material is distributed evenly and without voids along the wheel's circumference. In a technical implementation, the recompressor can be a recompressor piston. During a recompression phase in the casting process, the recompressor piston can extend in a recompressor stroke into a displacement chamber of a rear horn partial cavity of the die-casting tool, creating local pressure. Preferably, a number of secondary compressors are positioned evenly distributed around the circumference of the wheel. The secondary compressors are divided into a group of radial secondary compressors and a group of axial secondary compressors. The radial secondary compressors are arranged radially outside the rear horn partial cavity of the die-casting tool. In this case, the radial secondary compressors can act on the rear horn partial cavity via a radial secondary compressor piston stroke. In contrast, the axial secondary compressors are arranged axially adjacent to the rear horn partial cavity of the die-casting tool, preferably at right angles to the radial secondary compressors. The axial secondary compressors can act on the rear horn partial cavity of the die-casting tool via an axial secondary compressor piston stroke. Due to t