US20170136527A1

US20170136527A1 - High pressure die cast machine

Info

Publication number: US20170136527A1
Application number: US14/942,395
Authority: US
Inventors: Qigui Wang; Michael J. Walker
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2015-11-16
Filing date: 2015-11-16
Publication date: 2017-05-18
Also published as: CN106694839A; DE102016121024A1

Abstract

A high pressure die casting apparatus for forming metal components includes a die cast mold, a shot sleeve, and a plunger. The shot sleeve includes a pivotable pouring lid disposed in an inlet of the shot sleeve. The pouring lid is disposed in at least one of a closed position and an open position while having a pouring profile shape for promoting smooth non turbulent flow of liquid metal from a pouring ladle to the shot sleeve.

Description

TECHNICAL FIELD

The present disclosure relates to metal casting processes and more particularly to a high pressure die cast machine.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
A high pressure die cast machine introduces liquid metal, particularly an aluminum or magnesium alloy, into a permanent die cast mold at a higher pressure than typical gravity feed mold processes. The high pressure serves many process needs including the requirement to continue to feed the mold with liquid metal as the casting solidifies and shrinks. The means for increasing pressure of the incoming metal may be one of many examples including employing a shot sleeve and piston mechanism. Furthermore, high pressure die cast processes produce a high quality part requiring less machining than other cast processes. However, the high pressure die cast process is vulnerable to several pitfalls to which other processes may be more immune. For example, when injecting the liquid metal into the mold, much more of the metal that is injected is retained in the finished part. Therefore, if there are higher oxides and inclusions due to turbulence when pouring the metal, those oxides and inclusions will solidify in the finished casting and result in a scrap part.
While current high pressure die cast machines achieve their intended purpose, the need for new and improved high pressure die cast machines which exhibit improved performance, especially from the standpoints of scrap rates and casting quality, is constant. Accordingly, there is a need in the art for an improved high pressure die cast machine that improves upon these performance properties.

SUMMARY

The present invention provides a high pressure die casting apparatus for forming metal components. The high pressure die casting apparatus includes a die cast mold, a shot sleeve, and a plunger. The die cast mold has a stationary first mold and a movable second mold combining to form an interior mold cavity. The first mold includes a gate system hydraulically connected to the mold cavity. The shot sleeve includes an interior shot chamber, an inlet opening, a pouring lid, a first end, and a second end opposite the first end. The first end of the shot sleeve has an opening and hydraulically connects the shot chamber to the gate system of the first mold. The inlet is disposed in the shot sleeve. The pouring lid is disposed in the inlet opening. The plunger is disposed in the shot chamber. The plunger is configured to translate laterally through the shot chamber from the second end to the first end. The pouring lid is disposed in at least one of a closed position and an open position. In the closed position, the pouring lid is disposed in the inlet of the shot sleeve. In the open position, the pouring lid is pivoted such that the shot chamber is open.
In another example of the present invention, the pouring lid has a first end and a second end opposite the first end. The first end is pivotably mounted in the inlet opening of the shot sleeve.
In yet another example of the present invention, the pouring lid includes a resilient member for urging the pouring lid to the open position.
In yet another example of the present invention, the plunger urges the pouring lid to the closed position as the plunger translates laterally through the shot chamber towards the first end of the shot chamber.
In yet another example of the present invention, the pouring lid has a concave pouring profile surface.
In yet another example of the present invention, the pouring lid includes a pouring basin.
In yet another example of the present invention, the second end of the pouring lid includes an edge having a radius. The second end of the pouring lid fits to the interior surface of the shot chamber when the pouring lid is in the open position.
In yet another example of the present invention, the high pressure die casting apparatus is operated according to a method of operation having several steps.
In yet another example of the present invention, the method of operation includes a first through a seventh step. The first step provides the high pressure die cast machine with the pouring lid in the closed position. The second step actuates the pouring lid to the open position. The third step pours liquid metal from a pouring ladle onto the pouring lid and into the shot chamber. The fourth step actuates the pouring lid to the closed position after the shot chamber has a prescribed amount of liquid metal poured into the shot chamber. The fifth step actuates the plunger through the shot chamber and fills the mold cavity with the liquid metal. The sixth step retracts the plunger to an initial position. The seventh step opens the mold after solidification of the part, ejects the part, closes the mold, and returns to the second step of the method of operation.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross sectional schematic of a high pressure die cast machine in accordance with the present invention;

FIG. 2 is a cross sectional schematic of a high pressure die cast machine in accordance with the present invention;

FIG. 3 is a cross sectional schematic of a high pressure die cast machine in accordance with the present invention;

FIG. 4 is a cross sectional schematic of a shot sleeve pouring lid of a high pressure die cast machine in accordance with the present invention; and

FIG. 5 is a flow chart depicting the process flow of the operation of a high pressure die cast machine in accordance with the present invention.

DESCRIPTION

Referring to the drawings, wherein like reference numbers refer to like components, in FIG. 1 a high pressure die cast machine 10 is shown in accordance with an example of the present invention and will now be described. In general, the high pressure die cast machine 10 includes a set of high pressure die cast molds 12, a shot sleeve 14, a shot plunger 16, and a piston assembly 17. More particularly, the set of die cast molds 12 are specifically designed to create a particular part shape and thus are exchangeable with other dies in the high pressure die cast machine 10. The set of die cast molds 12 includes at least a moveable mold 18 and a stationary mold 20. When the molds 18, 20 are in a closed position, the molds 18, 20 form a mold cavity 22 and a gating system 24. The gating system 24 is a plurality of passages or runners that hydraulically connects the mold cavity 22 to the exterior of the molds 18, 20. The gating system 24 is contained in the stationary mold 20 although some portions of the gating system 24 may also be formed in the moveable mold 18. Furthermore, the set of die cast molds 12 may include other apparatuses or systems including a cooling system, a heating system, and an ejection system, etc. without departing from the scope of the invention.
The shot sleeve 14 is an elongated vessel having a first end 26, second end 28 opposite the first end 26, and a constant cross-sectional shape 30 from the first end 26 to the second end 28 creating a shot chamber 32. The first end 26 of the shot sleeve 14 is adjacent to the set of cast dies 12; and in particular to the stationary mold 20 of the set of cast dies 12. The first end 26 includes an orifice or opening 34 that hydraulically connects the shot chamber 32 with the gating system 24 of the stationary mold 20.
The shot sleeve 14 further includes an inlet 52 and a pouring lid 54. The inlet 52 is placed on the top of the shot sleeve 14 and allows the liquid metal 56 to be poured into the shot chamber 32. The pouring lid 54 is disposed in the inlet 52. More specifically, the pouring lid 54 is pivotably mounted in the inlet 52 at a pivot point 58 located closest to the second end 28 of the shot sleeve 14. Further details of the pouring lid 54 will be described below.
The piston assembly 17 is disposed adjacent to the second end 28 of the shot sleeve 14 and includes a first end 36, a second end 38, a cylindrical piston chamber 40, a piston 42, and a connecting bar or rod 44. For example, the first end 36 of the piston assembly 17 is adjacent the second end 28 of the shot sleeve 14 and shares a sealed bore 46 in common with the second end 28 of the shot sleeve 14. The piston 42 is slidably disposed in the piston chamber 40 and fixed to a first end 48 of the connecting rod 44. A second end 50 of the connecting rod 44 extends through the sealed bore 46 of the second end 28 of the shot sleeve 14 into the shot chamber 32 of the shot sleeve 14. The shot plunger 16 is fixed to the second end 50 of the connecting rod 44 such that the piston 42, the connecting rod 44, and the shot plunger 16 translate laterally in common. The shot plunger 16 is profiled to fit the shot chamber 32.
Turning now to FIGS. 2 and 3 with continuing reference to FIG. 1, the operation of the high pressure die cast machine 10 is illustrated and will now be described. In particular, FIG. 2 shows a pouring ladle 60 full of a liquid aluminum alloy 56 pouring the liquid aluminum 56 onto the pouring lid 54 of the shot sleeve 14. The pouring lid 54 is urged into the open position to open the shot chamber 32 of the shot sleeve 14 to receive the liquid aluminum 56. The pouring lid 54 rests against a bottom wall 62 of the shot chamber 32 such that the pouring lid 54 and the bottom wall 62 of the shot chamber 32 form an angle α of approximately 20° to 70°. The angle α formed by the pouring lid 54 and the shot chamber 32 bottom wall 62 promotes a smooth lamellar flow of liquid aluminum 56 from the ladle 60 into the shot chamber 32 and discourages turbulent flow which results in a minimal amount of liquid aluminum 56 exposed to the atmosphere.
Turning now to FIG. 3, the plunger 16 stroke of the process is illustrated and will now be described. Specifically, the liquid aluminum 56 has been completely deposited into the shot chamber 32. Next, the plunger 16 is translated through the shot chamber 32 first urging the pouring lid 54 to a closed position and second forcing the liquid aluminum 56 through the shot chamber 32, through the gating system 24 of the mold 20, and into the mold cavity 22. A further function of the pouring lid 54 is to cover the inlet 52 of the shot sleeve 14 to prevent liquid aluminum 56 from splashing out of the inlet 52 during the initial shot profile of the plunger 16. The pouring lid 54 is made from a high temperature resistant material such as a spring steel or a ceramic, however, other types of high temperature materials may be considered without departing from the scope of the invention. Furthermore, while the material chosen for the pouring lid 54 may be rigid and inflexible, a pouring lid 54 may be constructed from a flexible or partially flexible material without departing from the scope of the invention.
Referring now to FIG. 4, a pouring lid 70 is illustrated in detail and will now be described. The pouring lid 70 includes a first end 71, a second end opposite the first end 73, a pivot point 72, a spring 74 or other resilient mechanism, a pouring profile surface 76, and a pouring basin 78. More specifically, the pivot point 72 of the pouring lid 70 is disposed at the first end 71 of the pouring lid 70 and is a pin, hinge, or other pivoting mechanism used to rotate the pouring lid 70 about the pivot point 72. The spring 74 is disposed at the pivot point 72 to keep the pouring lid 70 in a normally open position. However, other mechanisms can be used to perform this task without departing from the scope of the invention. For example, a lever and counterweight apparatus or a pneumatic system may be employed to perform a similar function. The pouring lid may include the pouring basin 78 disposed proximate the pivot point 72 of the pouring lid 70.
The pouring profile surface 76 includes a number of shaped surfaces and edges configured to promote smooth transition of liquid aluminum 56 from the pouring ladle 60, onto the pouring lid 70, and into the shot chamber 32. For example, the pouring lid 70 includes a tailing edge 80 disposed on the second end 73 of the pouring lid 70 and configured with a radius that fits the inside radius of the shot chamber 32. Furthermore, pouring profile surface 76 includes a concave surface 82 configured to receive the liquid aluminum 56 on a nearly vertical surface 84 and transition to a nearly horizontal surface 86 as the liquid aluminum flows off the pouring lid 70 and into the shot chamber 32. Additionally, when the pouring lid 70 is in the closed position, the bottom surface 75 of the pouring lid 70 includes a radius to conform to the cross-section of the shot chamber 32 thus allowing the plunger 16 to pass through the shot chamber 32 when the pouring lid 70 is closed.
Turning now to FIG. 5 with continuing reference to FIGS. 1-4, a flowchart depicting the process method 100 for the high pressure die cast machine 10 is illustrated and will now be described. The first step 112 of the method of casting a high pressure die cast part starts by providing a high pressure die cast machine 10 with a pouring lid 54 in a closed position (see FIG. 1). The second step 114 includes actuating the pouring lid 54 to a pivoted or open position. The third step 116 includes pouring liquid metal 56 from a pouring ladle 60 onto the pouring lid 54 and into the shot chamber 32 (see FIG. 2). The fourth step 118 includes actuating the pouring lid 54 to the closed position while the shot chamber 32 has a prescribed amount of liquid metal 56 (as show in FIG. 3). The fifth step 120 includes actuating the plunger 16 through the shot chamber 32 and filling the mold cavity 22 with the liquid metal 56. The sixth step 122 includes opening the mold 12 after solidification of the part, ejecting the part, closing the mold. The plunger 16 is held in its extended position to help promote proper cooling of the part and also aid in ejecting the part. The seventh step 124 includes retracting the plunger 16 to an initial position and returning to the second step 114.
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and examples for practicing the invention within the scope of the appended claims.

Claims

The following is claimed:

1. A high pressure die casting apparatus for forming metal components, the high pressure die casting apparatus including:

a die cast mold having a stationary first mold and a movable second mold combining to form an interior mold cavity, and wherein the first mold includes a gate system hydraulically connected to the mold cavity;

a shot sleeve including an interior shot chamber, an inlet opening, a pouring lid, a first end, and a second end opposite the first end, and wherein the first end of the shot sleeve has an opening that hydraulically connects the shot chamber to the gate system of the first mold, the inlet is disposed in the shot sleeve, and the pouring lid is disposed in the inlet opening, and

a plunger disposed in the shot chamber, and wherein the plunger is configured to translate laterally through the shot chamber from the second end to the first end; and

wherein the pouring lid is disposed in at least one of a closed position and an open position; in the closed position the pouring lid is disposed in the inlet of the shot sleeve, and in the open position the pouring lid is pivoted such that the shot chamber is open.

2. The high pressure die cast apparatus of claim 1, wherein the pouring lid has a first end and a second end opposite the first end, the first end is pivotably mounted to the shot sleeve in the inlet opening.

3. The high pressure die cast apparatus of claim 2, wherein the pouring lid includes a resilient member for urging the pouring lid to the open position.

4. The high pressure die cast apparatus of claim 3 wherein the plunger urges the pouring lid to the closed position as the plunger translates laterally through the shot chamber towards the first end of the shot chamber.

5. The high pressure die cast apparatus of claim 4 wherein the pouring lid has a concave pouring profile surface.

6. The high pressure die cast apparatus of claim 5 wherein the pouring lid includes a pouring basin.

7. The high pressure die cast apparatus of claim 6 wherein the second end of the pouring lid includes an edge having a radius and the second end of the pouring lid fits to the interior surface of the shot chamber when the pouring lid is in the open position.

8. A high pressure die casting apparatus for forming metal components, the high pressure die casting apparatus including:

a shot sleeve including an interior shot chamber, an inlet opening, a first end, and a second end opposite the first end, and wherein the first end of the shot sleeve has an opening that hydraulically connects the shot chamber to the gate system of the first mold, and the inlet is disposed in the shot sleeve;

a pouring lid having a first end and a second end opposite the first end, and wherein the first end of the pouring lid is pivotably mounted in the inlet opening, and

wherein the pouring lid is disposed in at least one of a closed position and an open position; in the closed position the pouring lid is disposed in the inlet of the shot sleeve; in the open position the pouring lid is pivoted such that the shot chamber is open, and the high pressure die casting apparatus is operated according to a method of operation having several steps.

9. The high pressure die cast apparatus of claim 8, wherein the pouring lid includes a resilient member for urging the pouring lid to the open position.

10. The high pressure die cast apparatus of claim 8 wherein the plunger urges the pouring lid to the closed position as the plunger translates laterally through the shot chamber towards the first end of the shot chamber.

11. The high pressure die cast apparatus of claim 8 wherein the pouring lid has a concave pouring profile surface.

12. The high pressure die cast apparatus of claim 8 wherein the pouring lid includes a pouring basin.

13. The high pressure die cast apparatus of claim 8 wherein the second end of the pouring lid includes an edge having a radius and the second end of the pouring lid fits on to the interior surface of the shot chamber when the pouring lid is in the open position.

14. The high pressure die cast apparatus of claim 8, wherein the method of operation includes:

a first step of providing the high pressure die cast machine with the pouring lid in the closed position;

a second step of actuating the pouring lid to the open position;

a third step of pouring liquid metal from a pouring ladle onto the pouring lid and into the shot chamber;

a fourth step of actuating the pouring lid to the closed position while the shot chamber has a prescribed amount of liquid metal;

a fifth step of actuating the plunger through the shot chamber and filling the mold cavity with the liquid metal;

a sixth step of retracting the plunger to an initial position; and

a seventh step of opening the mold after solidification of the part, ejecting the part, closing the mold, and returning to the second step of the method of operation.

15. A pouring lid for a high pressure die cast apparatus, the pouring lid including a first end and a second end opposite the first end, and wherein the first end of the pouring lid is pivotably mounted in an inlet opening of a shot chamber of the high pressure die cast apparatus.

16. The pouring lid of claim 15, wherein the pouring lid includes a resilient member for urging the pouring lid to an open position.

17. The pouring lid of claim 16, wherein a plunger of the high pressure die cast apparatus urges the pouring lid to a closed position as the plunger translates laterally through the shot chamber.

18. The pouring lid of claim 17 wherein the pouring lid has a concave pouring profile surface.

19. The pouring lid of claim 18 wherein the pouring lid includes a pouring basin.

20. The pouring lid of claim 19 wherein the second end of the pouring lid includes an edge having a radius and the second end of the pouring lid fits to an interior surface of the shot chamber when the pouring lid is in the open position.