U.S. patent application number 13/533149 was filed with the patent office on 2013-12-26 for advanced feed system for semi solid casting.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS LLC. The applicant listed for this patent is Qigui Wang, Wenying Yang. Invention is credited to Qigui Wang, Wenying Yang.
Application Number | 20130340967 13/533149 |
Document ID | / |
Family ID | 49754324 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130340967 |
Kind Code |
A1 |
Yang; Wenying ; et
al. |
December 26, 2013 |
Advanced Feed System for Semi Solid Casting
Abstract
A feed system for introducing semi-solid metal alloy to a die
casting machine includes a first chamber for receiving a metal
alloy billet and for preparing the semi-solid metal alloy billet.
The first chamber includes heaters and a cutting system. The metal
alloy billet is heated by the heaters and cut by the cutting system
into predetermined lengths to form semi-solid metal alloy portions.
The feed system also includes a second chamber connected to the
first chamber by a passage to receive the semi-solid metal alloy
portions. The second chamber includes a door that opens and closes
the passage and a plunger system that introduces the semi-solid
metal portions to a die cast machine. An atmosphere control system
is in fluid communication with the first chamber and the second
chamber. The atmosphere control system removes oxygen from the feed
system. A method using the feed system is also provided.
Inventors: |
Yang; Wenying; (Rochester
Hills, MI) ; Wang; Qigui; (Rochester Hills,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yang; Wenying
Wang; Qigui |
Rochester Hills
Rochester Hills |
MI
MI |
US
US |
|
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS
LLC
Detroit
MI
|
Family ID: |
49754324 |
Appl. No.: |
13/533149 |
Filed: |
June 26, 2012 |
Current U.S.
Class: |
164/68.1 ;
164/113; 266/207; 266/236 |
Current CPC
Class: |
B22D 17/30 20130101;
B22D 17/007 20130101 |
Class at
Publication: |
164/68.1 ;
266/236; 266/207; 164/113 |
International
Class: |
B22D 17/30 20060101
B22D017/30; B22D 27/00 20060101 B22D027/00 |
Claims
1. A feed system for semi-solid metal casting, the system
comprising: a first chamber for receiving a metal alloy billet, the
first chamber including heaters and a cutting system, the metal
alloy billet being heated by the heaters and cut by the cutting
system into predetermined lengths to form semi-solid metal alloy
portions; a second chamber connected to the first chamber by a
passage to receive the semi-solid metal alloy portions, the second
chamber including a door that opens and closes the passage and a
plunger system that introduces the semi-solid metal portions to a
die cast machine; and an atmosphere control system for removing
oxygen from the feed system, the atmosphere control system being in
fluid communication with the first chamber and the second chamber,
the atmosphere control system including an inert gas purging system
that introduces an inert gas into the first chamber via inlet port
and then into the second chamber via the passage.
2. The feed system of claim 1 wherein the plunger system includes a
plunger that pushes the semi-solid metal into the die cast
machine.
3. The feed system of claim 2 wherein the plunger is positionable
in a first position such that the second chamber receives the
semi-solid metal and a second position in which the door is
closed.
4. The feed system of claim 3 wherein the plunger system further
includes a sheath that operates as the door, the sheath moving with
the plunger.
5. The feed system of claim 4 wherein the plunger system further
includes a biasing member that acts to move the sheath towards the
die cast machine.
6. The feed system of claim 3 wherein the plunger system further
includes a hydraulic system for moving the plunger.
7. (canceled)
8. The feed system of claim 1 wherein inert gas is introduced into
the second chamber.
9. The feed system of claim 1 wherein the metal alloy billet
comprises an alloy with a freezing range.
10. The feed system of claim 1 wherein the metal alloy billet
comprises an aluminum alloy.
11. The feed system of claim 10 wherein the aluminum alloy
comprises aluminum and a component selected from the group
consisting of copper, magnesium, manganese, silicon, zinc, and
combinations.
12. The feed system of claim 10 wherein the aluminum alloy
comprises aluminum and silicon.
13. The feed system of claim 10 wherein the metal alloy billet
comprises a component selected from the group consisting of
magnesium alloys, tin alloys, zinc alloys, and copper alloys.
14. A feed system for semi-solid metal casting, the system
comprising: a first chamber for receiving an alloy billet, the
first chamber including heaters and a cutting system, wherein the
alloy billet is heated by the heaters and cut by the cutting system
into predetermined lengths to form semi-solid metal portions, a gas
purging system providing a positive pressure of an inert gas to the
first chamber; and a second chamber connected to the first chamber
by a passage, the second chamber including a door that opens and
closes the passage and a plunger system that introduces the
semi-solid metal portions to a die cast machine.
15. A method of feeding alloy billet to a die cast machine, the
method comprising: introducing the alloy billet into a first
chamber including heaters and a cutting system; heating the alloy
billet in a first chamber under a substantially oxygen free
environment to a temperature at which the alloy billet is a
semi-solid; cutting the alloy billet in the first chamber into
semi-solid metal alloy portions having a predetermined length;
introducing the semi-solid metal alloy portions into a second
chamber through a passage between the first and second chamber, the
second chamber including a door that opens and closes the passage
and a plunger system; and introducing the semi-solid metal alloy
portions into the die cast machine by the plunger system.
16. The method of claim 15 wherein inert gas is introduced into the
second chamber.
17. The method of claim 15 wherein the alloy billet comprises an
alloy with a freezing range.
18. The method of claim 17 wherein the alloy billet comprises an
aluminum alloy.
19. The method of claim 18 wherein the aluminum alloy comprises
aluminum and a component selected from the group consisting of
copper, magnesium, manganese, silicon, zinc, and combinations.
20. The method of claim 18 wherein the aluminum alloy comprises
aluminum and silicon.
Description
[0001] The present invention relates to methods for metal casting,
and particularly feed systems and methods for semi-solid metal
(SSM) casting parts.
BACKGROUND OF THE INVENTION
[0002] Semi-solid metal (SSM) casting, also known as semi-solid
forming, is a hybrid manufacturing method that incorporates
elements of both casting and forging. Semi-solid metal casting
(SSM) is a near net shape variant of die casting. Die casting is a
popular metal forming technique for forming metal or metal alloy
parts. Die casting finds broad application in diverse technologies
such as automotive parts, plane parts, toys, utensils, and the
like. In the typical die casting process, a molten metal or metal
alloy is forced under high pressure into a mold cavity.
[0003] Unlike typical die casting, SSM process is to introduce raw
materials with nondendritic microstructure in the semi-solid state.
SSM is done at a temperature that puts the metal between its
liquidus and solidus temperature. Ideally, the metal should be 30
to 65% solid. The metal must have a low viscosity to be usable, and
to reach this low viscosity the material needs a globular primary
surrounded by the liquid phase. The temperature range possible
depends on the material and for aluminum alloys is 5-10.degree. C.,
but for narrow melting range copper alloys can be only several
tenths of a degree.
[0004] Semi-solid metal (SSM) casting is typically used for
high-end castings with non-ferrous metals, such as aluminum,
copper, and magnesium. For aluminum alloys typical parts include
engine suspension mounts, air manifold sensor harness, engine
blocks and oil pump filter housing.
[0005] In SSM process, the metal is usually prepared for
introduction into a die cast machine by cutting a metal or metal
alloy billet into predefined lengths and widths. The feedstock is
then heated up into the semi-solid state and introduced into the
casting machine. Since the metal is typically heated in ambient
before being placed in the casting machine, the metal (surface) is
subject to oxygen contamination often with a layer of oxide forming
on the metal portions. Such contamination can degrade the quality
of the parts being formed resulting in performance problems.
[0006] Accordingly, the present invention provides improved methods
of making high quality semi-solid metal castings with the proposed
advanced feed system and methods of making
SUMMARY OF THE INVENTION
[0007] The present invention solves one or more problems of the
prior art by providing, in at least one embodiment, a feed system
for semi-solid metal casting. The feed system includes a first
chamber for receiving a metal alloy billet. The first chamber
includes heaters and a cutting system. The metal alloy billet is
heated by the heaters and cut by the cutting system into
predetermined lengths to form semi-solid metal alloy portions. The
feed system also includes a second chamber connected to the first
chamber by a passage to receive the semi-solid metal alloy
portions. The second chamber includes a door that opens and closes
the passage and a plunger system that introduces the semi-solid
metal portions to a die cast machine. An atmosphere control system
is in fluid communication with the first chamber and the second
chamber. The atmosphere control system removes oxygen from the feed
system.
[0008] In another embodiment, a feed system for semi-solid metal
casting is provided. The feed system includes a first chamber for
receiving a metal alloy billet. The first chamber also includes
heaters and a cutting system. The metal alloy billet is heated by
the heaters and cut by the cutting system into predetermined
lengths to form semi-solid metal portions. A second chamber is
connected to the first chamber by a passage. The second chamber
includes a door that opens and closes the passage and a plunger
system that introduces the semi-solid metal portions to a die cast
machine. A gas purging system is in fluid communication with and
provides a positive pressure of an inert gas to the first chamber
and second chamber.
[0009] In another embodiment, a method of feeding metal alloy
billet to a die cast machine using the feed systems set forth above
is provided. The method includes a step of introducing the alloy
billet into a first chamber which has heaters and a cutting system.
The alloy billet is heated in a first chamber under a substantially
oxygen free environment to a temperature at which the alloy billet
is a semi-solid. The alloy billet is then cut in the first chamber
into semi-solid metal alloy portions having a predetermined length.
The semi-solid metal alloy portions are introduced into a second
chamber through a passage between the first and the second chamber.
The second chamber includes a door that opens and closes the
passage and a plunger system. The semi-solid metal alloy portions
are introduced into the die cast machine by the plunger system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Exemplary embodiments of the present invention will become
more fully understood from the detailed description and the
accompanying drawings, wherein:
[0011] FIG. 1 provides a schematic illustration of a feed system
for feeding semi-solid metal or metal alloy to a die casting
machine; and
[0012] FIGS. 2A, 2B, and 2C provide a schematic flowchart of a
method of feeding semi-solid metal alloy to a die casting machine
using the system of FIG. 1.
DESCRIPTION OF THE INVENTION
[0013] Reference will now be made in detail to presently preferred
compositions, embodiments and methods of the present invention,
which constitute the best modes of practicing the invention
presently known to the inventors. The Figures are not necessarily
to scale. However, it is to be understood that the disclosed
embodiments are merely exemplary of the invention that may be
embodied in various and alternative forms. Therefore, specific
details disclosed herein are not to be interpreted as limiting, but
merely as a representative basis for any aspect of the invention
and/or as a representative basis for teaching one skilled in the
art to variously employ the present invention.
[0014] Except in the examples, or where otherwise expressly
indicated, all numerical quantities in this description indicating
amounts of material or conditions of reaction and/or use are to be
understood as modified by the word "about" in describing the
broadest scope of the invention. Practice within the numerical
limits stated is generally preferred. Also, unless expressly stated
to the contrary: percent, "parts of," and ratio values are by
weight; the description of a group or class of materials as
suitable or preferred for a given purpose in connection with the
invention implies that mixtures of any two or more of the members
of the group or class are equally suitable or preferred;
description of constituents in chemical terms refers to the
constituents at the time of addition to any combination specified
in the description, and does not necessarily preclude chemical
interactions among the constituents of a mixture once mixed; the
first definition of an acronym or other abbreviation applies to all
subsequent uses herein of the same abbreviation and applies mutatis
mutandis to normal grammatical variations of the initially defined
abbreviation; and, unless expressly stated to the contrary,
measurement of a property is determined by the same technique as
previously or later referenced for the same property.
[0015] It is also to be understood that this invention is not
limited to the specific embodiments and methods described below, as
specific components and/or conditions may, of course, vary.
Furthermore, the terminology used herein is used only for the
purpose of describing particular embodiments of the present
invention and is not intended to be limiting in any way.
[0016] It must also be noted that, as used in the specification and
the appended claims, the singular form "a," "an," and "the"
comprise plural referents unless the context clearly indicates
otherwise. For example, reference to a component in the singular is
intended to comprise a plurality of components.
[0017] Throughout this application, where publications are
referenced, the disclosures of these publications in their
entireties are hereby incorporated by reference into this
application to more fully describe the state of the art to which
this invention pertains.
[0018] The term "billet" as used herein refers to a raw metal stock
such as a bar stock. Therefore, a metal alloy billet is a metal
alloy bar stock.
[0019] With reference to FIG. 1, a schematic illustration of a feed
system for feeding semi-solid metal or metal alloy to a die casting
machine is provided. Feed system 10 introduces metal alloy billet
into die casting machine 12. Feed system 10 includes first chamber
14 that receives metal alloy billet 16 into receiving section 18.
In a refinement, metal alloy 16 is manually introduced into first
chamber 14. In another refinement, metal alloy billet 16 is
provided to first chamber 14 by motorized drive system 20. First
chamber 14 also includes heaters 22 and cutting system 24. Metal
alloy billet 16 is heated by heaters 22 to a sufficient temperature
so that the billet becomes semi-solid. Metal alloy billet 16 is cut
by cutting system 24 into predetermined lengths to form semi-solid
metal alloy portions. The lengths that are cut are chosen to
provide sufficient material for a part that is to be formed in die
cast system 12. The semi-solid metal alloy portions are received
into the transfer section of chamber 14. Feed system 10 also
includes second chamber 28 connected to first chamber 14 by passage
30. Second chamber 28 includes door 32 that opens and closes
passage 30. Second chamber 28 also includes plunger system 36 which
introduces the semi-solid metal portions to die cast machine
12.
[0020] Still referring to FIG. 1, atmosphere control system 40 is
in fluid communication with first chamber 14 and second chamber 28.
Atmosphere control system 40 removes oxygen from the feed system.
In a refinement, atmosphere control system 40 is an inert gas
purging system that introduces an inert gas into the first chamber
via inlet port 42. Typically, the inert gas is then introduced into
the second chamber via passage 30. Examples of suitable inert gases
include nitrogen, helium, argon and the like. In another
refinement, atmosphere control system 40 is a vacuum system that
excludes oxygen by maintaining feed system 10 at reduced pressure.
Optional controller 41 may be used to control both the heaters and
atmosphere control system 40.
[0021] Still referring to FIG. 1, plunger system 36 includes
plunger 44 that pushes the semi-solid metal portions into die cast
machine 12. Plunger 36 is positionable in a first position P1 such
that the second chamber receives the semi-molten metal portion and
in a second position P2 in which door 32 is closed. In the specific
variation illustrated in FIG. 1, plunger system 36 further includes
sheath 46 that operates as door 32 by moving with plunger 44. In
this variation, section 48 of sheath 46 blocks passage 30 when
plunger 42 is at position P2 while when at position P1, passage 30
is open. In a refinement, plunger system 36 further includes a
biasing member such as spring 50 that contacts the sheath and acts
to provide a biasing force that acts to moves sheath 46 towards die
cast machine 12. In a refinement, plunger system 30 further
includes hydraulic system 52 for moving the plunger between
positions P1 and P2.
[0022] With reference to FIGS. 1 and 2A-C, a method of feeding
metal alloy to a die cast machine is provided. FIGS. 2A-C provide a
schematic flowchart of the method. Feed system 10 receives an alloy
billet 16 into first chamber 14 as set forth in step a). In
particular, alloy billet 16 is received into receiving section 18.
As set forth above, first chamber 12 includes heaters 22 and
cutting system 24. In step b), alloy billet 16 is heated in the
first chamber 16 under a substantially oxygen free environment to a
temperature at which the alloy billet 16 is a semi-solid which is
identified by item number 16' in FIG. 2A. Oxygen is excluded by the
atmosphere control system by either inert gas purging or by
maintaining the first chamber 14 under a vacuum. In step c), alloy
billet 16 is cut in the first chamber 14 into semi-solid metal
alloy portions 56 having a predetermined length. In step d), the
semi-solid metal alloy portions 56 are introduced into (e.g.,
transported to) the second chamber 28 through passage 30 between
the first and the second chambers. It should be appreciated that
plunger 44 is positioned at position P1 so that passage 30 is open
and one of the semi-solid metal alloy portions 56 can enter the
second chamber 28. In step e), plunger 44 is moved to position P2
causing section 48 of sheath 46 to block passage 30. In step f),
plunger 44 is moved further along direction d.sub.1 so that one of
the semi-solid metal alloy portions 56 is introduced into die
casting machine 12. In step g), plunger 30 returns to position P1
so that another semi-solid metal alloy portion may be transported
to the second chamber 28.
[0023] As set forth above, the variations and embodiments of the
feed system and related method are used to introduce alloys into a
die casting system. In a refinement, the metal alloy billets
include an alloy with a freezing range (between liquidus and
solidus). The presence of a freezing range will typically mean that
the purely liquid and solid phases do not concurrently exist within
this range. In a further refinement the freezing range is from
about 5 to about 100 degrees C., depending alloy compositions. In
another refinement, the metal alloy billet comprises an aluminum
alloy. Such aluminum alloys typically include aluminum and a
component selected from the group consisting of copper, magnesium,
manganese, silicon, zinc, and combinations. In such aluminum
alloys, the amount of aluminum is from about 80 weight percent to
about 99.95 weight percent and the amount of other alloying
elements is from about 0.05 to about 20 weight percent. In many
aluminum alloys, the amount of aluminum is less than about 99
weight percent. Many cast aluminum alloys are hypoeutectic alloys
having aluminum dendritic phase forming first during
solidification. For example, one type of useful aluminum alloy
includes aluminum and silicon. In such alloys, the amount of
silicon is usually from about 4 to 14 weight % with the balance
being aluminum (86 to 96 weight percent) or aluminum plus other
alloying elements (0.05 to 20 weight percent) as above. In another
refinement, the alloy billet comprises a component selected from
the group consisting of magnesium alloys, tin alloys, zinc alloys,
and copper alloys.
[0024] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *