CROSS-REFERENCE TO RELATED APPLICATION

[0001] This PCT International Patent Application claims the benefit of U.S. Provisional Patent Application Serial No. 63/314,779, filed on February 28, 2022 and titled “Process Control For Tailored Tempered Properties,” the entire disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0002] The present invention relates to a shot sleeve for high pressure vacuum die casting, a high pressure vacuum die casting system including the shot sleeve, and a method of high pressure vacuum die casting a metal part using the shot sleeve.

2. Related Art

[0003] This section provides background information related to the present disclosure which is not necessarily prior art.

[0004] A high pressure vacuum die casting machine can be used to form metal parts, such as parts for vehicles. The high pressure vacuum die casting process uses a vacuum pump to remove air or other gases from a die cavity of the die casting machine before injecting molten metal into the die cavity. A shot sleeve is connected to the die cavity, and a ladle or vacuum dosing unit provides the molten metal to the shot sleeve. The molten metal enters through a pour hole of the shot sleeve, and a plunger presses the molten metal from the shot sleeve into the die cavity.

[0005] The conventional ladle and dosing of the molten metal into the shot sleeve can provide a shot of the molten metal of up to approximately 50 kg, which is sufficient for die casting machines that have a clamping force tonnage of 4,440 tons. However, the amount of molten metal that can be provided by the ladle and the conventional dosing method is limited. The ladle and conventional dosing method are not able to provide acceptable shots which are large enough for use in larger die casting machines. For example the ladle and conventional dosing method are not able to provide acceptable shot sizes greater than 120 kg, which are needed for ultra-large giga castings, such as those formed by die casting machines that have a clamping force tonnage of 6, 100 tons. If the metal shot is greater than 120 kg, at least a portion of the shot would become too cool during the time required to fill the shot sleeve with the large shot. The cool material could limit the flow length, and the casting produced by the die casting machine could exhibit cold defects. Pouring the molten metal into the pour hole of the shot sleeve faster in attempt to prevent the metal from getting too cold induces additional turbulence and subjects the shot sleeve to aggravated wash out and/or erosion, which could lead to higher maintenance costs, for example due to frequent replacement of the shot sleeve.

[0006] Accordingly, a shot sleeve, high pressure vacuum die casting system, and method for high pressure vacuum die casting of larger parts is needed.

SUMMARY

[0007] This section provides a general summary of the disclosure and is not to be interpreted as a complete and comprehensive listing of all of the objects, aspects, features and advantages associated with the present disclosure.

[0008] One aspect of the subject disclosure provides a shot sleeve for conveying molten metal to a high pressure vacuum die casting machine which is capable of manufacturing an ultralarge giga casting. The shot sleeve includes a plurality of pour holes for receiving the molten metal. [0009] Another aspect of disclosure is a high pressure vacuum die casting machine including the shot sleeve with the plurality of pour holes. The shot sleeve receives the molten metal from one or more ladles and one or more additional sources, such as a crucible. The shot sleeve is connected to and conveys the molten metal to a die cavity of the high pressure vacuum die casting machine.

[0010] Another aspect of the disclosure is a method of high pressure die casting a metal part using the shot sleeve. The method includes providing the molten metal though the plurality of openings of the shot sleeve, conveying the molten metal through the shot sleeve and to the die cavity, and casting the molten metal in the die cavity.

[0011] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings described herein are for illustrative purposes only of selected embodiments and are not intended to limit the scope of the present disclosure. The inventive concepts associated with the present disclosure will be more readily understood by reference to the following description in combination with the accompanying drawings wherein:

[0013] Figure 1 is a perspective view of a shot sleeve including multiple pour holes according to an example embodiment;

[0014] Figure 2 shows a ladle and crucibles providing molten metal to a shot sleeve including multiple pour holes according to an example embodiment;

[0015] Figure 3 illustrates a ladle according to an example embodiment;

[0016] Figure 4 shows a vacuum dosing furnace according to an example embodiment; [0017] Figure 5 shows a crucible containing an ultrasonic sonotrode according to an example embodiment;

[0018] Figure 6 shows a high pressure vacuum die casting machine capable of manufacturing ultra-large giga castings;

[0019] Figure 7 is a graph illustrating die casting machine capability; and

[0020] Figure 8 illustrates a conventional shot sleeve for purposes of comparison.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0021] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments are only provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well- known device structures, and well-known technologies are not described in detail.

[0022] One aspect of the subject disclosure provides a shot sleeve 10 for conveying molten metal, such as aluminum or aluminum alloy, to a high pressure vacuum die casting machine 12 which is capable of casting parts that require shot sizes greater than 120 kg. For example, the shot sleeve 10 can be used to manufacture ultra-large giga castings, such as those formed by die casting machines that have a clamping force tonnage of 6,100 tons. The shot sleeve 10 is capable of manufacturing these castings without cold defects and without subjecting the shot sleeve 10 to aggravated wash out and/or erosion, which could lead to higher maintenance costs, for example due to frequent replacement of the shot sleeve 10.

[0023] Figures 1 and 2 illustrate the shot sleeve 10 according to example embodiments. The shot sleeve 10 is typically formed of metal, such as steel. The shot sleeve 10 includes a side wall 14 surrounding a center axis and extending longitudinally from a first end 16 to a second end 18. The side wall 14 defines a passageway for holding molten metal and conveying molten metal to the die casting machine 12. The passageway defines a volume of at least 180 liters which is capable of holding shots greater than 235 kg with a fill ratio ranging from 35% to 50%. The fill ratio is the percentage of the total volume of the shot sleeve that is occupied by the shot of the molten metal. For example, if the fill ratio is 35%, then the shot occupies 35% of the total volume of the shot sleeve.

[0024] The shot sleeve 10 includes multiple pour holes 20, 22 for receiving the shot of molten metal. According to the example embodiment shown in Figures 1 and 2, the top of the shot sleeve 10 includes a conventional main pour hole 20 for receiving the molten metal and allowing the molten metal to enter the passageway. In this embodiment, the main pour hole 20 is disposed closer to the second end 18 of the shot sleeve 10 than the first end 16 of the shot sleeve 10.

[0025] The shot sleeve 10 also includes at least one auxiliary pour hole 22 in addition to the main pour hole 20. Typically, two auxiliary pour holes 22 are disposed at an angle relative to the main pour hole 20. In the embodiment of Figures 1 and 2, the shot sleeve 10 includes two auxiliary pour holes 22 located near the top of the shot sleeve 10 and between the first end 16 of the shot sleeve 10 and the main pour hole 20. The two auxiliary pour holes 22 are disposed on opposite sides of the main pour hole 20 and they are located at an equal distance from the center axis of the shot sleeve 10. However, the shot sleeve 10 could include more than two auxiliary pour holes 22, and the auxiliary pour holes 22 could be disposed at other locations. Due to the multiple pour holes 20, 22, an entire shot ranging from 100 kg to 235 kg or greater can be quickly poured into the shot sleeve 10 without a portion of the shot becoming too cool.

[0026] Various different sources can be used to provide the molten metal to the shot sleeve 10, such as those shown in Figures 2-5. A conventional automated ladle machine 24 typically obtains the molten metal from a holding furnace and pours the molten metal into the main pour hole 20 of the shot sleeve 10. Figures 2 and 3 show the conventional automated ladle machine 24 according to an example embodiment.

[0027] At least one additional pouring source 26 also provides the molten metal to the shot sleeve. The additional pouring source(s) 26 could obtain the molten metal from the same holding furnace as the ladle machine 24. Alternatively, space permitting, two holding furances could provide the molten metal, one for ladle 24 and the other for the additional pouring source(s) 26. The two holding furnaces could have an added feature to compensate for temperature loss due to larger pouring weight. Or, one of the holding furnaces could maintain the molten metal at a higher temperature, depending on temperature loss, to compensate for temperature loss due to larger pouring weight.

[0028] Preferably, a vacuum dosing furnace 26, such as a furnace provided by MEL TEC, provides the molten metal to the shot sleeve 10 in addition to the conventional automated ladle machine 24. An example of the vacuum dosing furnace 26 is shown in Figure 4. The vacuum dosing furnace 26 includes at least one crucible 28, for example two crucibles 28, which convey the molten metal through the auxiliary pour holes 22 of the shot sleeve 10. Examples of the crucibles 28 are shown in Figures 2, 4, and 5. Each of the vacuum dosing crubicles 28 could be equipped with an ultrasonic sonotrode 30, as shown in Figure 5, to further degass and process the molten metal.

[0029] In the example embodiments, the crucibles 28 include heads formed of ceramic. The two vacuum dosing crucible heads would have a clearance between the tip of the ceramic crucible head and the shot sleeve 10, so that the two ceramic crucible heads remain in a pouring position, thus covering the auxiliary pour holes 22. Any metal spillage due to plunger movement would re-enter the crucibles 28 which would later be equalized after fdling and ultrasonic treatment during the next cycle. The additional vacuum dosing crucibles 28 would pour at an angle instead of straight down, like the ladle 24. The two auxiliary pour holes 22 could be slightly offset so that they do not directly hit each other and in order to minimize turbulence during fdling. Therefore, a large amount of molten aluminum (120 kg or more) fdls the shot sleeve 10 faster, with better temperature control, and less turbulence with high quality metal. Figure 6 illustruates a high pressure vacuum die casting machine 12 which includes the shot sleeve 10 with multiple pour holes 22. This high pressure vacuum die casting machine 12 is capable of manufacturing ultralarge giga castings. Figure 7 is a graph illustrating die casting machine capability.

[0030] The conventional dosing method which includes a single ladle providing the molten metal to a single pour hole of the shot sleeve is not able to provide shot sizes greater than 120 kg, which are needed for the ultra-large giga castings. Figure 8 illustrates a conventional shot sleeve for purposes of comparison. A shot size of greater than 120 kg would tend to get cold as it sits in the shot sleeve waiting to get fdled with more metal. The cold material could limit the flow length, and the casting produced by the die casting machine could exhibit cold defects. Pouring the molten metal into the pour hole of the shot sleeve faster in attempt to prevent the metal from getting too cold induces additional turbulence and subjects the shot sleeve to aggravated wash out and/or erosion, which could lead to higher maintenance costs, for example due to frequent replacement of the shot sleeve.

[0031] It should be appreciated that the foregoing description of the embodiments has been provided for purposes of illustration. In other words, the subject disclosure it is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varies in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of disclosure.