Three-Plate Die Casting Mold Having a Sprue System and Improved Sprue Separation, and Die Casting Method

Abstract

A three-plate die casting mold for producing a metal die-cast part by die casting a molten metal includes a first, second, and third mold part, where the third mold part is disposed between the first and second mold parts. Molten metal is feedable to a die cavity through a sprue system where the sprue system has a plurality of feed channels that are disposed in the third mold part and open into the die cavity. The plurality of feed channels have a respective tapering at a die cavity-side end where the respective tapering locally decreases a channel cross section such that a predetermined breaking point is generated during a die casting operation which allows a defined separation of the metal die-cast part from a sprue created in the sprue system when the three-plate die casting mold is being opened.

Claims

1.-9. (canceled)

10. A three-plate die casting mold for producing a metal die-cast part by die casting a molten metal, comprising: a first mold part; a second mold part; a third mold part, wherein the third mold part is disposed between the first mold part and the second mold part; a die cavity; and a sprue system, wherein the molten metal is feedable to the die cavity through the sprue system and wherein the sprue system has a plurality of feed channels that are disposed in the third mold part and open into the die cavity; wherein the plurality of feed channels in the third mold part that open into the die cavity have a respective tapering at a die cavity-side end and wherein the respective tapering locally decreases a channel cross section such that a predetermined breaking point is generated during a die casting operation which allows a defined separation of the metal die-cast part from a sprue created in the sprue system when the three-plate die casting mold is being opened.

11. The three-plate die casting mold as claimed in claim 10, wherein the plurality of feed channels each have a conical form.

12. The three-plate die casting mold as claimed in claim 10, wherein the taperings are each formed by a respective bead around a periphery that is disposed in the channel cross section.

13. The three-plate die casting mold as claimed in claim 10, wherein the first mold part is formed with a plurality of pins which project into respective feed channels when the three-plate die casting mold is closed and wherein the plurality of pins are each formed with an undercut contour which retains the sprue when the three-plate die casting mold is being opened.

14. The three-plate die casting mold as claimed in claim 13, wherein the plurality of pins are each in a form of an ejector for the sprue.

15. The three-plate die casting mold as claimed in claim 10, wherein the plurality of feed channels open perpendicularly into the die cavity.

16. A method for producing a metal die-cast part by the three-plate die casting mold as claimed in claim 10, comprising the steps of: providing the three-plate die casting mold; closing the three-plate die casting mold and performing a die casting operation to create the metal die-cast part, wherein a molten metal is pressed through the sprue system into the die cavity; opening the three-plate die casting mold after the molten metal has solidified, wherein the created metal die-cast part is separated from a sprue created in the sprue system in a defined way at predetermined breaking points generated by the taperings.

17. The method as claimed in claim 16, wherein during the opening, the three-plate die casting mold is opened first in a mold parting plane between the third mold part and the first mold part, wherein the created metal die-cast part has been separated from the sprue already at a start of the opening.

18. The method as claimed in claim 16, wherein the created metal die-cast part is a vehicle component.

19. The method as claimed in claim 18, wherein the vehicle component is a thin-walled light-metal bodywork component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 schematically shows a three-plate die casting mold according to the invention; and

[0023] FIGS. 2 to 4 schematically illustrate the mode of operation of the three-plate die casting mold according to the invention on the basis of a detail of the mold, selected by way of example, in accordance with the region A identified in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

[0024] The three-plate die casting mold 100 shown in FIG. 1 is installed in a die casting machine, which is not shown, and comprises a first, in particular stationary, mold part 110 (first mold plate), a second, movable mold part 120 (second mold plate) and a third mold part 130 (third mold plate), which is arranged between the first mold part 110 and the second mold part 120 and is likewise movable. The die casting mold 100 further comprises a die cavity 140, for example for producing a thin-walled light-metal bodywork component, and a sprue system 150, through which liquid molten metal enters the die cavity 140. The sprue system 150 may have a similar configuration, for example, to that described in DE 10 2012 107 363 A1.

[0025] The three-plate die casting mold 100 advantageously allows a lateral feed, substantially perpendicular with respect to an areal extent of the die-cast part to be produced, of the molten metal to the die cavity 140. For this purpose, the sprue system 150 has multiple conical, and as a result nozzle-shaped, feed channels 151 (also referred to as gates) which are arranged in the third mold part 130 or formed in the third mold part 130 and open into the die cavity 140, in particular substantially perpendicularly.

[0026] A first mold parting point or mold parting plane T1 is located between the second mold part 120 and the third mold part 130, and a second mold parting point or mold parting plane T2 is located between the third mold part 130 and the first mold part 110. By moving or displacing the second mold part 120 and the third mold part 130, as illustrated by the arrows B1, B2, the die casting mold 100 can be opened at the mold parting planes T1, T2. It is then possible to remove the die-cast part created in the die cavity 140 by the solidified molten metal from the die by way of the first mold parting plane T1, and to remove the sprue created in the sprue system 150 by the solidified molten metal from the die by way of the second mold parting plane T2. When the three-plate die casting mold 100 is being opened, the die-cast part is forcibly separated from the sprue, as will be explained in more detail below.

[0027] FIG. 2 shows the situation after filling the cavity 140 with liquid molten metal by way of the sprue system 150 with the die casting mold 100 closed. The molten metal solidifies in the die cavity 140 to form a die-cast part 200 and in the sprue system 150 to form what is referred to as a sprue 300. A mandrel-like pin 160 (retaining pin), which is arranged on the first mold part 110, is formed with an undercut contour 165, and at its front end preferably likewise has a conical or at least semi-conical shape, is moved into the conical feed channel 151, which opens into the die cavity 140. (The same applies in particular also for the other feed channels or gates in the third mold part 130 that open into the die cavity 140.)

[0028] After the molten metal has solidified, the die casting mold 100 is opened in the second mold parting plane T2, as illustrated in FIG. 3. In the process, the die-cast part 200 located in the die cavity 140 is separated from the sprue 300 or from the sprue web 310 by being torn away. According to the invention, at its die cavity-side end, the feed channel 151, formed in the third mold part 130, of the sprue system 150 has a tapering 153 which locally decreases the channel cross section. (The same applies in particular also for the other feed channels in the third mold part 130 that open into the die cavity 140.) The tapering 153 is in the form of a peripheral bead or the like, in particular with a collar-like shape, in the opening cross section 152 to the die cavity 140, as can be seen in particular in FIG. 4.

[0029] As a result of the local tapering 153, during the die casting operation an annular groove-like, in particular annular notch-like, predetermined breaking point is generated between the die-cast part 200 and the sprue 300, at which predetermined breaking point a defined separation or tearing away of the die-cast part 200 from the sprue 300 (and specifically directly on the die-cast part 200) takes place already at the start of the opening movement B2 of the third mold part 130, wherein the sprue 300 or the sprue web 310 is retained as a result of a form fit with the undercut contour or with the undercut 165 on the pin 160, thereby favoring separation or tearing away. Only a small, flash-free tear-off point 210 remains on the die-cast part 200.

[0030] After the die casting mold 100 has been completely opened, as is shown in FIG. 4, the die-cast part 200 and the sprue 300 can be removed from the die. The sprue 300 is removed from the die using at least one ejector 170 in the first mold part 110 and also using the pressure piston 400 which is part of the die casting machine, as is illustrated by the arrows in FIG. 4. The pin or retaining pin 160 may optionally also act as an ejector, as indicated in dashed lines, in order to assist removal from the die. Accordingly, the pin 160 may also be in the form of an ejector. It is similarly possible for ejectors, not shown, to be provided in order to remove the die-cast part 200 from the die.

LIST OF REFERENCE CHARACTERS

[0031] 100 Three-plate die casting mold [0032] 110 First mold part (nozzle plate) [0033] 120 Second mold part (closing plate) [0034] 130 Third mold part (intermediate plate) [0035] 140 Die cavity [0036] 150 Sprue system [0037] 151 Feed channel [0038] 152 Opening cross section [0039] 153 Local tapering [0040] 160 Pin (mandrel) [0041] 165 Undercut contour (undercut) [0042] 170 Ejector [0043] 200 Die-cast part [0044] 210 Tear-off point [0045] 300 Sprue [0046] 310 Sprue web [0047] 400 Casting piston [0048] A Region [0049] B1 Opening movement [0050] B2 Opening movement [0051] T1 First mold parting plane [0052] T2 Second mold parting plane