Three-Plate Pressure Die Casting Mold Having Improved Sprue Separation, and Method for Pressure Die Casting

Abstract

A three-plate pressure die casting mold for producing at least one metallic die casting part by die casting a metal melt, includes first, second and third mold parts and at least one mold cavity as well as a sprue system. A relatively movable pressure plate is arranged in the third mold part, which, when opening the die casting mold, presses the sprue produced in the sprue system against the first mold part, whereby the sprue is retained and tears off from the die casting part in a defined manner. A method for pressure die casting using the three-plate pressure die casting mold is disclosed.

Claims

1.-10. (canceled)

11. A three-plate die casting mold for producing at least one metal die-cast part by die casting a metal melt, comprising: a first, a second, and a third mold part, with the third mold part being arranged between the first and the second mold parts; at least one die cavity; a sprue system, through which the metal melt is fed to the die cavity; and a relatively movable pressing plate arranged in the third mold part, wherein: when the die casting mold is being opened, a sprue created in the sprue system is torn off from the die-cast part created in the die cavity and the die-cast part is removable by way of a first mold parting plane between the second mold part and the third mold part, and the sprue is removable by way of a second mold parting plane between the first mold part and the third mold part, and when the die casting mold is being opened in the second mold parting plane, the relatively movable pressing plate in the third mold part presses the sprue against the first mold part, whereby the sprue is retained and tears off from the die-cast part in a defined manner.

12. The three-plate die casting mold according to claim 11, wherein the pressing plate is mounted in the third mold part via guide elements.

13. The three-plate die casting mold according to claim 11, wherein the pressing plate is pretensioned by at least one spring device.

14. The three-plate die casting mold according to claim 13, wherein the third mold part is formed with a pocket in which the spring device is arranged.

15. The three-plate die casting mold according to claim 13, wherein the spring device is a disk spring set.

16. The three-plate die casting mold according to claim 11, wherein the third mold part has an adjustment mechanism for the pressing plate.

17. The three-plate die casting mold according to claim 16, wherein the adjustment mechanism is a cam slider mechanism.

18. The three-plate die casting mold according to claim 11, wherein the sprue system has multiple feed channels, which are arranged in the third mold part, lead into the die cavity, and, at their die-cavity-side ends, are each formed with a tapering which locally reduces a channel cross section and which creates a predetermined breaking point during die casting operation at which the sprue tears off from the die-cast part.

19. A method for producing at least one metal die-cast part, comprising: providing a three-plate die casting mold comprising: a first, a second, and a third mold part, with the third mold part being arranged between the first and the second mold parts; at least one die cavity; a sprue system, through which the metal melt is fed to the die cavity; and a relatively movable pressing plate arranged in the third mold part, wherein a first mold parting plane is between the second mold part and the third mold part, and a second mold parting plane is between the first mold part and the third mold part; closing the die casting mold and carrying out a die casting operation, with metal melt being pressed into the die cavity through the sprue system; opening the die casting mold after the metal melt has solidified, with a sprue created in the sprue system being pressed against the first mold part by the pressing plate in the second mold parting plane and tearing off from the die-cast part.

20. The method according to claim 19, wherein the die-cast part to be produced is a vehicle component.

Description

BRIEF DESCRIPTION THE DRAWINGS

[0026] FIG. 1 schematically shows a three-plate die casting mold according to an embodiment of the invention.

[0027] FIGS. 2 to 4 schematically depict the mode of operation of the die casting mold of FIG. 1 with reference to a mold detail selected by way of example (according to the region A identified in FIG. 1).

[0028] FIG. 5 schematically shows a preferred first possible embodiment for actuating the pressing plate in the die casting mold of FIGS. 1 to 4.

[0029] FIG. 6 schematically shows an alternative second possible embodiment for actuating the pressing plate in the die casting mold of FIGS. 1 to 4.

DETAILED DESCRIPTION THE DRAWINGS

[0030] The three-plate die casting mold 100 shown in FIG. 1 is incorporated 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 likewise is movable. The first mold part 110 may optionally have a sprue plate 111 in the form of an insert. The third mold part 130 has a relatively movable pressing plate 160, as explained in more detail below. The die casting mold 100 also comprises a die cavity 140, for example for producing a thin-walled light metal bodywork component, and a sprue system 150, through which liquid metal melt (for example aluminum melt or magnesium melt) enters, or is pressed into, the die cavity 140. The sprue system 150 can, for example, have a similar configuration to that described in DE 10 2012 107 363 A1. (In the figures, and nonlimitingly, only one die cavity 140 is illustrated, it also being possible for a three-plate die casting mold 100 according to the invention to have multiple die cavities.)

[0031] The three-plate die casting mold 100 advantageously makes it possible to feed the metal melt to the die cavity 140 laterally, and substantially perpendicularly with respect to an areal extent of the die-cast part to be produced. To that end, the sprue system 150 has multiple conical, and thus 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 which lead, in particular substantially perpendicularly, into the die cavity 140. (In the figures, and nonlimitingly, only one of the feed channels 151 is illustrated, the explanations below referring to this one feed channel 151. A three-plate die casting mold 100 according to the invention may have multiple such feed channels 151 or only one such feed channel 151.)

[0032] There is a first mold parting plane T1 between the second mold part 120 and the third mold part 130, and a second mold parting plane T2 between the third mold part 130 and the first mold part 110. These mold parting planes T1, T2 are not planar surfaces in the mathematical sense, but complexly shaped mold parting points that are, however, referred to as mold parting planes. Moving, or displacing, the second mold part 120 and the third mold part 130, as depicted by the arrows B1, B2, makes it possible to open the die casting mold 100 at the mold parting planes T1, T2. Then, the die-cast part created in the die cavity 140 by the solidified metal melt can be removed from the die by way of the first mold parting plane T1, and the sprue created in the sprue system 150 by the solidified metal melt can be removed from the die by way of the second mold parting plane T2, as explained in more detail below with reference to FIGS. 2 to 4.

[0033] FIG. 2 shows the situation after the cavity 140 has been filled with liquid metal melt by way of the sprue system 150, with the die casting mold 100 closed. The metal melt 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, what is referred to as a sprue web 310 forming in the feed channel 151 of the sprue system 150.

[0034] After the metal melt has solidified, the die casting mold 100 is firstly opened in the second mold parting plane T2, as illustrated in FIG. 3. Here, the sprue 300 is pressed against the first mold part 110 by means of the pressing plate 160, as depicted by the arrows F. As a result, the sprue 300 is clamped in, as it were, and extensively retained. Because of the further opening movement B2, the sprue 300, or the sprue web 310, is separated, or torn off, from the die-cast part 200. The pressing plate 160 positions the sprue 300 in a defined manner for the sprue separation and the subsequent ejection operation.

[0035] The pressing plate 160 is arranged so as to be relatively movable in the third mold part 130 and is longitudinally movably mounted, or guided, by means of multiple guide elements 161 in such a way that it can move parallel to the opening movement B1/B2, that is to say horizontally. The guide elements 161 may be in the form of protruding guide stubs, which dip into the first mold part 110 when the die casting mold 100 is being closed, or are dipped in the first mold part (110) when the die casting mold 100 is in the closed state. This simplifies the mounting and maintenance of the pressing plate 160, which can be pushed in onto the protruding guide stubs and taken off of them. The guiding length is also increased.

[0036] The actuation, or application of force, can be effected by means of at least one spring device or by means of an adjustment mechanism (see FIG. 5 and FIG. 6). The end face of the pressing plate 160 is provided in particular such that an admissible surface pressure is not exceeded. The pressing plate 160 is in the form of a mold part and can also be considered to be a fourth mold part, or fourth mold plate. In the region of the feed channel 151, the pressing plate 160 has a cutout, it also being possible to provide that the feed channel 151 extends directly through the pressing plate 160, or is at formed least partially in the pressing plate 160.

[0037] The feed channel 151, formed in the third mold part 130, of the sprue system 150 has, at its die-cavity-side end, a tapering 153 that locally decreases the channel cross section. (The same applies in particular also for the other feed channels 151 in the third mold part 130 that lead into the die cavity 140.) In the opening cross section 152 to the die cavity 140, the tapering 153 is in the form of a bead or the like that runs around the periphery, in particular that is shaped in collar-like fashion (as can be seen in particular in FIG. 4). The local tapering 153 creates an annular-groove-like, in particular annular-notch-like, predetermined breaking point between the die-cast part 200 and the sprue 300 during the die casting operation, at which predetermined breaking point the sprue 300 is separated, or torn off, from the die-cast part 200 in a defined manner (and specifically directly at the die-cast part 200) already just after the start of the opening movement B2 of the third mold part 130, with the sprue 300, or the sprue web 310, being retained by means of the relatively movable pressing plate 160, thereby ensuring defined separation, or tearing off. Only a small, flash-free tear-off point 210 remains on the die-cast part 200.

[0038] The movement travel of the pressing plate 160 toward the first mold part 110 is delimited by a mechanical stop (see FIG. 5 and FIG. 6), with the result that the pressing plate 160, in the course of the further opening movement B2, lifts off from the sprue 300 and releases it (as shown in FIG. 4). After the die casting mold 100 has completely opened, the die-cast part 200 and the sprue 300 can be removed from the die. The removal of the sprue 300 from the die is effected by means of at least one ejector 170 in the first mold part 110, and optionally also by means of the casting piston 400 that is part of the die casting machine and ejects the butt. Ejectors, which are not shown, can likewise be provided to remove the die-cast part 200 from the die.

[0039] FIG. 5 shows (without structural detail) a first possible embodiment, in which the relatively movable pressing plate 160 is actuated by means of multiple spring devices 162. The spring devices 162 are in particular in the form of disk spring sets. The relatively movable pressing plate 160 is pretensioned toward the first mold part 110, or toward the sprue 300, by the spring devices 162. The spring devices 162 are arranged in pockets 132 formed in the main body 131 of the third mold part 130. Such pockets may also be formed in the pressing plate 160. The pockets 132 may be produced by machining, for example by milling. Also schematically illustrated is a stop 133, which delimits the travel of the pressing plate 160. The movement travel of the pressing plate 160 that is enabled, or the pressing plate stroke, must correspond at least to the opening travel, or the tear-off travel, of the third mold part 130 until tearing off occurs (what is meant by this is the tearing off of the sprue 300 from the die-cast part 200) and is in particular greater than the tear-off travel. The spring devices 162 are in particular designed such that the pressing plate 160 is not pressed against the stop 133 or is pressed against it only with a small force, in order to avoid excessive actions of force on the stop 133.

[0040] FIG. 6 shows (without structural detail) a second possible embodiment, in which the relatively movable pressing plate 160 is actuated by an adjustment mechanism, which is arranged substantially in the third mold part 130 and is in the form of a cam slider mechanism.

[0041] The actuation is effected in particular in a travel-controlled manner depending on the opening movement B2 of the third mold part 130. The cam slider mechanism has multiple cam sliders 165 that are driven mechanically (for example by way of a slotted guide), electromechanically, or by an electric motor, or hydraulically, optionally also pneumatically. Depending on the drive, the pressing plate 160 may also be pretensioned by the cam slider mechanism, that is to say virtually resilient cam sliders 165 are provided instead of the spring devices 162 shown in FIG. 5. The cam angle makes it possible to predefine a determined force transmission ratio and/or travel transmission ratio. The explanations above relating to the possible embodiment shown in FIG. 5 apply analogously to the stop 133 and the pressing plate travel.

[0042] In the case of the two possible embodiments shown in FIGS. 5 and 6, when the die casting mold 100 is being closed, the pressing plate 160 is reset, the resetting force being applied directly by the first mold part 110. The second possible embodiment shown in FIG. 6 may have resetting springs, which draw back the pressing plate 160 once the cam sliders 165 are moved back, in order for example, when the die casting mold 100 is open, to provide more space to remove the sprue 300 from the die.

LIST OF REFERENCE SIGNS

[0043] 100 Three-plate die casting mold [0044] 110 First mold part (nozzle plate) [0045] 111 Sprue plate [0046] 120 Second mold part (closing plate) [0047] 130 Third mold part (intermediate plate) [0048] 131 Main body [0049] 132 Pocket [0050] 133 Stop [0051] 140 Die cavity [0052] 150 Sprue system [0053] 151 Feed channel [0054] 152 Opening cross section [0055] 153 Local tapering [0056] 160 Pressing plate [0057] 161 Guide element [0058] 162 Spring device [0059] 165 Cam slider [0060] 170 Ejector [0061] 200 Die-cast part [0062] 210 Tear-off point [0063] 300 Sprue [0064] 310 Sprue web [0065] 400 Casting piston [0066] A Region [0067] B1 Opening movement [0068] B2 Opening movement [0069] F Compressive force [0070] T1 First mold parting plane [0071] T2 Second mold parting plane