U.S. patent application number 16/344845 was filed with the patent office on 2020-02-13 for composite part with external part cast around internal insert and method for producing the same.
The applicant listed for this patent is Shiloh Industries, Inc.. Invention is credited to Sam A. Kassoumeh, Alexandre Reikher.
Application Number | 20200047243 16/344845 |
Document ID | / |
Family ID | 62076353 |
Filed Date | 2020-02-13 |
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United States Patent
Application |
20200047243 |
Kind Code |
A1 |
Reikher; Alexandre ; et
al. |
February 13, 2020 |
COMPOSITE PART WITH EXTERNAL PART CAST AROUND INTERNAL INSERT AND
METHOD FOR PRODUCING THE SAME
Abstract
Composite parts and methods for making the same are disclosed. A
composite part may include an internal insert component that is
coated on at least a portion of its surface with certain types of
particles, an external part component cast around the coated
insert, and a particle-rich region that is formed between the two
components, where the particle-rich region includes particles from
the coated insert. A method for producing a composite part may
include the steps of: positioning an internal insert component that
is coated on at least a portion of its surface within a mold cavity
of a casting die; casting a molten material of the external part
component around the coated insert; and solidifying the molten
material to form the external part component of the composite
part.
Inventors: |
Reikher; Alexandre;
(Pleasanton, CA) ; Kassoumeh; Sam A.; (Canton,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shiloh Industries, Inc. |
Valley City |
OH |
US |
|
|
Family ID: |
62076353 |
Appl. No.: |
16/344845 |
Filed: |
November 1, 2017 |
PCT Filed: |
November 1, 2017 |
PCT NO: |
PCT/US2017/059572 |
371 Date: |
April 25, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62415896 |
Nov 1, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 2945/76083
20130101; B29C 2945/76294 20130101; B22D 19/08 20130101; B22D 19/14
20130101; B22D 19/00 20130101; B22D 17/24 20130101; B29C 45/14073
20130101 |
International
Class: |
B22D 17/24 20060101
B22D017/24; B22D 19/08 20060101 B22D019/08 |
Claims
1. A composite metal part, comprising: an internal insert component
that is made from a first metal material and includes a coating on
at least a portion of an outer surface; an external part component
that is made from a second metal material and is cast around at
least a portion of the internal insert component; and a
particle-rich region that includes a plurality of dispersed
particles from the coating and is located between the internal
insert component and the external part component, wherein the first
metal material is different than the second metal material.
2. The composite metal part of claim 1, wherein the particle-rich
region includes an intermetallic layer formed from the first metal
material, the second metal material, and the coating.
3. The composite metal part of claim 1, wherein the particle-rich
region forms a layer between the first and second metal materials
having a thickness of approximately 20 micrometers (.mu.m) to 180
micrometers (.mu.m), inclusive.
4. The composite metal part of claim 1, wherein the first metal
material includes a magnesium-based material.
5. The composite metal part of claim 1, wherein the internal insert
component is hollow.
6. The composite metal part of claim 1, wherein the second metal
material includes an aluminum-based material.
7. The composite metal part of claim 6, wherein the aluminum-based
material includes one of an aluminum A380 alloy, an A360 alloy, an
Aural-2 alloy, or an ADC12 alloy.
8. The composite metal part of claim 6, wherein both the coating on
the internal insert component and the plurality of dispersed
particles in the particle-rich region include at least one material
selected from the group consisting of: a silicon-based material, a
titanium-based material, an oxide, or a carbide.
9. The composite metal part of claim 1, wherein the composite metal
part is a steering knuckle.
10. The composite metal part of claim 1, further comprising a
support pin engaged with the internal insert component and cast
with the external part component.
11. The composite metal part of claim 1, wherein the external part
component defines a gap along an outer surface, thereby partially
exposing the internal insert component.
12. The composite metal part of claim 1, wherein the particles of
the coating of the internal insert component are initially applied
in a substantially homogeneous distribution about the portion of
the outer surface of the internal insert component.
13. A method of forming a composite part having an internal insert
component and an external part component, comprising the steps of:
positioning the internal insert component within a mold cavity,
wherein the internal insert component comprises a first metal
material, and wherein at least a portion of an outer surface of the
internal insert component is covered with a coating comprising a
plurality of particles; casting a molten material around the
internal insert component, the molten material comprising a second
metal material different from the first metal material; and
solidifying the molten material to form the external part component
of the composite part, thereby dispersing the particles to form a
particle-rich region located between the internal insert component
and the external part component.
14. The method of claim 13, further comprising cooling the internal
insert component as the molten material is cast around the internal
insert.
15. The method of claim 13, wherein the first metal material
includes a magnesium-based material, and the second metal material
includes an aluminum-based material.
16. The method of claim 15, wherein both the coating on the
internal insert component and the plurality of dispersed particles
in the particle-rich region include at least one material selected
from the group consisting of: a silicon-based material, a
titanium-based material, an oxide, or a carbide.
17. The method of claim 13, wherein the coating is distributed
substantially homogeneously about the portion of the outer surface
of the internal insert component.
18. The method of claim 17, wherein a percentage by weight of the
coating varies no more than 12% along the portion of the outer
surface of the internal insert component prior to the casting of
the molten material.
19. The method of claim 13, further comprising cooling the
particle-rich region using a directed cooling path to the internal
insert component.
20. The method of claim 19, wherein the cooling path is along a
support pin supporting the internal insert component in the mold
cavity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application Ser. No. 62/415,896, filed on Nov. 1, 2016, the
contents of which are hereby expressly incorporated by reference in
their entirety.
FIELD
[0002] The present disclosure relates to composite parts and, more
particularly, to composite parts having a lightweight internal
insert component and a die cast external part component.
BACKGROUND
[0003] Composite parts employing different materials may
advantageously provide a blend of material properties. For example,
a first material may provide relative strength or durability, while
a second material different from the first may provide light weight
or other desirable characteristics.
[0004] Composite parts are often difficult to assemble or form due
to differing material properties of the multiple materials used.
Merely as one example, one material may have a different
coefficient of thermal expansion than another, and as a result the
two materials may respond differently during any hot forming
technique (e.g., casting) or cooldown from the same. More
specifically, the different rates of thermal expansion may result
in cracks, dislocations, gaps, or the like between the different
materials. As a result, a bond between the different materials may
be weakened or otherwise negatively affected.
[0005] Accordingly, there is a need for a composite part that
addresses the above shortcomings.
DRAWINGS
[0006] FIG. 1 is a perspective view of an example of a composite
part having an internal insert component and an external part
component;
[0007] FIG. 2 is a front view of an example of a high pressure die
casting fixture;
[0008] FIG. 3A is a front view of the casting die of FIG. 2,
illustrating molten metal material being placed into a shot sleeve
of the fixture;
[0009] FIG. 3B is a front view of the casting die of FIG. 2,
illustrating a plunger forcing the molten metal material through
the shot sleeve;
[0010] FIG. 3C is a front view of the casting die of FIG. 2,
illustrating the die opening after a metallic part is
solidified;
[0011] FIG. 3D is a front view of the casting die of FIG. 2,
illustrating ejector pins forcing the metallic part out of the
die;
[0012] FIG. 4A is a perspective view of a two-piece internal insert
component that is placed within a casting die, such as that
illustrated in FIG. 2, where molten metal material can flow and
solidify around the insert so that the insert becomes integrated
within the composite part, according to one example;
[0013] FIG. 4B is a perspective view of the internal insert
component of FIG. 4A, shown assembled and partially sectioned;
[0014] FIG. 4C is a section view of the internal insert component
of FIGS. 4A and 4B, shown installed in a casting die such as that
illustrated in FIG. 2;
[0015] FIG. 5A is a lateral view of the internal insert component
of FIGS. 4A-4C, shown installed in a casting die that includes
several different examples of insert supports for holding the
insert in place within the casting die;
[0016] FIG. 5B is a lateral view of an insert support for holding
an internal insert component in place within a casting die,
according to one example;
[0017] FIG. 5C is a lateral view of an insert support for holding
an internal insert component in place within a casting die that has
a cooling channel provided within the die, according to one
example;
[0018] FIG. 5D is a lateral view of an insert support for holding
an internal insert component in place within a casting die that has
a phase change material provided within a support pin, according to
one example;
[0019] FIG. 5E is a lateral view of an insert support for holding
an internal insert component in place within a casting die, where
the support pin is permanently fixed to the die, according to one
example;
[0020] FIG. 5F is a lateral view of an insert support for holding
an internal insert component in place within a casting die, where
the support pin is configured to provide liquid cooling, according
to one example;
[0021] FIG. 5G is a lateral view of an insert support for holding
an internal insert component in place within a casting die, where
the support pin is permanently fixed within the die and is
configured to provide active cooling by way of a phase change
material, according to one example;
[0022] FIG. 5H is a longitudinal view of a composite part formed
with an insert support used to support an internal insert
component, where the insert support is permanently cast-in with the
composite part;
[0023] FIG. 6A is a sectional view of a finished composite part
having an internal insert component and an external part component
cast about the insert, according to one example;
[0024] FIG. 6B is another sectional view of a finished composite
part having an internal insert component and an external part
component, which is enlarged to show an interface region between
the insert and part components;
[0025] FIG. 7A is a perspective view of an internal insert
component for use in forming a composite part, according to one
example;
[0026] FIG. 7B is a perspective view of the internal insert
component shown in FIG. 7B, with a cap attached to an end of the
insert;
[0027] FIG. 7C is a cutaway view of a composite part formed with
the internal insert component shown in FIGS. 7A and 7B, according
to one example;
[0028] FIG. 7D is another cutaway view of the composite part of
FIG. 7C, according to one example; and
[0029] FIG. 8 is a process flow diagram for a method of forming a
composite part where an external part component is cast and
solidifies around an internal insert component during a die casting
process, according to one example.
DESCRIPTION
[0030] Exemplary illustrations are provided herein of a composite
part having an internal insert component and an external part
component where the external part is cast and solidifies around the
internal insert during a die casting operation, as well as methods
and equipment for forming the same. The composite part is suitable
for any number of applications, particularly those that seek to
reduce the weight of the part, yet retain much of its strength. The
terms "internal insert component," "internal insert," "insert
component," "coated insert" and "insert" are used interchangeably
in the present application, as are the terms "external part
component," "external part," "part component," "cast part,"
"metallic part," etc.
[0031] According to a non-limiting example, a composite part
includes an internal insert component that is made of a
magnesium-based material and is coated on at least a portion of its
surface with certain types of particles, an external part component
that is made of an aluminum-based material or zinc-based material
and is cast around the coated insert, and a particle-rich region
that is formed between the two components, where the particle-rich
region includes particles from the coated insert. The particle-rich
region may generally improve material properties of the outer
material, e.g., the aluminum or zinc material, for example by
creating a more refined microstructure, and in some cases may
improve bonding between the two components, e.g., by addressing
differences in their coefficients of thermal expansion (COE). For
instance, magnesium has a significantly higher COE than aluminum
and, thus, experiences substantially more expansion and contraction
in the presence and absence of heat. The particle-rich region is
designed to reduce the undesirable effects of these differences, as
well as that of oxide films on the surface of the internal insert
component which can contribute to the formation of gaps between the
two components. Macro, micro or even nano particles may be
pre-applied to a surface of the internal insert component to help
minimize such gaps and improve the bond between the components. In
the example above, the composite part includes an internal insert
component that is of a different material than the external part
component; however, this is not required, as the insert and part
components could both be formed from the same or similar materials,
as well materials other than those listed herein.
[0032] According to another non-limiting example, a potential
method for producing the composite part includes the steps of:
positioning an internal insert component that is coated on at least
a portion of its surface within a mold cavity of a casting die;
casting a molten material of the external part component around the
coated insert; cooling the coated insert as the molten material is
cast around it; forming a particle-rich region between the coated
insert and the part that is designed to offset differences in the
coefficients of thermal expansion (COE) of the two components;
solidifying the molten material to form the external part component
of the composite part; and ejecting the composite part from the
casting die.
[0033] As will be explained, one or more surfaces of the internal
insert component may be coated with particles according to a number
of techniques, including hot fusion, cold spraying, high velocity
spraying, electrodeposition, or application of the particles as the
insert is being formed (e.g., during a process of casting or
otherwise forming the insert), to cite a few possibilities. Of
course, any suitable technique for applying particles to an outside
surface of the insert may be employed. Some examples of suitable
particle materials include, but are not limited to: ceramic-based
particles, graphite, diamond, magnesium-based particles such as MgO
or MgAl.sub.2O.sub.4, aluminum oxide (Al.sub.2O.sub.3), silicon
(Si) and oxides thereof such as silicon oxide (SiO.sub.2), SiC,
titanium (Ti) and oxides thereof such as titanium oxide
(TiO.sub.2), TiB.sub.2, Cr 526, nickel, copper, zinc and zinc oxide
(ZnO.sub.2), silver and gold, to cite a few. In some examples
particles may be relatively small, such as less than 1.0 millimeter
in diameter or a maximum dimension thereof, and in some cases even
smaller, e.g., less than 0.25 millimeters or less than 0.10
millimeters, merely as examples. Additionally, other oxides (e.g.,
yttrium oxide or Y.sub.2O.sub.3), nitrides, carbides, hydrides, and
borides not specifically described above may be employed in
addition to or in lieu of examples noted above. Carbon black,
fullerenes and carbon nanotubes may also be used, as may
intermetallic compounds such as NiAl and Al.sub.3Ti.
[0034] While any of the above particles may be employed in example
illustrations, and although the particular particles used in a
particular application may depend on the materials used in the
internal insert component and/or the external part component,
typically silicon-based and titanium-based particles may be
particularly well-suited where aluminum-based alloy materials are
employed in the external part component. Oxides (e.g.,
Al.sub.2O.sub.3) and carbides may also be well-suited for such
applications.
[0035] It should be appreciated that the composite parts, methods
and equipment described herein may be used in a wide variety of
applications and industries. One particularly suitable application
for such composite parts is the automotive industry, where
lightweight parts such as steering knuckles, structural members,
cross members, control arms, etc. are desired.
[0036] Merely by way of example, with reference to FIG. 1, there is
shown a non-limiting example of a composite part in the form of a
steering knuckle 100. The steering knuckle 100 may include an
internal insert component 124, with an external part component 136
molded about the internal insert component 124.
[0037] The internal insert component 124 and external part
component 136 may be formed from similar or different materials.
For example, the external part component 136 may be formed from an
aluminum-based material (for example, an aluminum alloy, such as
aluminum A380 alloy, A360 alloy, Aural-2 alloy, or ADC12 alloy,
merely as examples) and have a wall thickness of 6 mm or greater,
while the internal insert component 124 may be formed from a
magnesium-based material. In a different example, both the internal
insert component 124 and the external part component 136 are made
from aluminum-based materials, perhaps the same aluminum alloy or
different aluminum alloys. Combinations of different materials in a
single part 100 in this manner may facilitate part characteristics
more ideally matched to a given application. For example, the
steering knuckle 100 is relatively lightweight owing to the use of
aluminum-based material in the external part component 136, but
also has increased strength compared with uniformly aluminum-based
parts owing to the use of magnesium-based materials for the
internal insert 124. Moreover, a bond strength between the internal
insert 124 and external part component 136 may be increased with
the use of a particle-rich region 140 formed from a coating
provided on at least a portion of the internal insert component 124
during the forming process of the steering knuckle 100. Other
materials combinations may be employed. Moreover, in some
applications it may be beneficial to form both the internal insert
component 124 and external part component 136 from similar or even
identical materials.
[0038] The particle-rich region 140 of the composite part 100 may
be formed in any number of suitable ways. In some examples,
particles are provided by applying a coating comprising the
particles to at least a portion of an internal insert component
prior to casting the external part component about the internal
insert component. Upon injection of molten material into the mold,
the molten material heats the internal insert component, and may
melt at least an outer layer of the internal insert component. This
outer layer of the internal insert component may generally mix with
the molten material, and the particles may disperse to a limited
extent within a particle-rich region or boundary area located
between the internal insert component and the molten material. The
molten material and any melted portion(s) of the internal insert
component may subsequently be cooled, thereby forming an
intermetallic layer where the position of the particles that have
been dispersed is generally fixed, creating a particle-rich region
between the internal insert component and the external part
component.
[0039] Of course, the methods, equipment and composite parts
described herein are not limited to such applications, as they are
merely provided as examples. In view of the wide range of
applications to which exemplary parts and methods may be directed,
the description that follows is directed to relatively simplified
part shapes to facilitate explanation of the exemplary
concepts.
Tooling System
[0040] As noted above, the composite parts described herein may be
formed in a casting process, where an external part component is
generally cast around an internal insert component. Referring now
to FIGS. 2 and 3A-3D, one example of a tooling system is
illustrated, which may be used for forming a composite part and/or
using any example methods described herein.
[0041] The tooling system 200 may include a mold for casting parts,
e.g., in a high pressure die cast process. The tooling 200
comprises a moveable/ejector half 202 and a stationary half 204.
The stationary half 204 may remain fixed, e.g., with respect to a
support surface (not shown in FIG. 2), while the ejector half 202
may move, for example to facilitate removal of parts formed within
the tooling 200, service/repair of the tooling 200, etc.
[0042] The ejector half 202 and stationary half 204 have an ejector
half cavity block 206 and stationary half cavity block 208,
respectively, which cooperate to define a mold for forming one or
more composite parts. The ejector half cavity block 206 and
stationary half cavity block 208 are supported by an ejector holder
block 210 and a stationary holder block 212, respectively.
[0043] Molten material (not shown in FIG. 2) may be injected into a
mold cavity 236 defined by the ejector half cavity block 206 and
stationary half cavity block 208 by way of a sleeve 216. For
example, molten material may be poured into a pour hole 220, and
forced into the mold cavity 236 by a plunger 218, as will be
described further below. The molten material may then enter the
mold cavity 236 by way of a runner 222, which extends from an end
of the sleeve 216 to the mold cavity 236.
[0044] As will be described further below, an internal insert
component 224 may be positioned within the mold cavity 236 so that
molten material can be cast around it. For example, one or more
locating pins 226 may be used to position and maintain the internal
insert component 224 within the mold cavity 236. Upon being
positioned within the mold cavity 236, molten material may be cast
about the internal insert component 224.
[0045] One or more cooling channels 228 may be provided adjacent
the mold cavity to facilitate management of a mold temperature
and/or cooling of molten material within the mold cavity 236.
Moreover, as will be described further below, in some examples
cooling passages or other features may be incorporated into or
located adjacent the locating pins 226. The locating pins 226 may
thereby facilitate cooling of the internal insert component 224 at
any point during the casting process. Cooling directed at the
internal insert component 224 in this manner may also facilitate
formation of a particle-rich region in the resulting composite
part, as will be discussed further below.
[0046] One or more ejector pin(s) 230 may be provided to facilitate
removal of a formed composite part from the mold cavity 236.
Although a single ejector pin 230 is illustrated in FIG. 2, any
number of additional ejector pins 230 may be provided that is
convenient. Ejector pin(s) 230 may be fixed at an end away from the
mold cavity 236 to a movable ejector plate 232, which slides along
a stationary support block 214. An ejector pin support plate 234
may also be provided, which may be fixed to the support block 214.
The support plate 234 may facilitate movement of the slidable
ejector plate 232 by providing a stationary reaction surface for
the ejector plate 232.
[0047] Referring now to FIGS. 3A-3D, the operation of the tooling
system 200 will be described in further detail. As shown in FIG.
3A, the internal insert component 224 may initially be positioned
within the mold cavity 236. The internal insert component 224, as
will be described further below, may have at least a portion of an
outer surface thereof coated with particles that are configured to
enhance bonding of the internal insert component 224 with a molten
material subsequently injected into the mold cavity 236 and into
contact with the outer surface of the internal insert component
224.
[0048] The internal insert component 224 may be located within the
mold cavity 236 using one or more locating pins 226, and a molten
material may be poured into sleeve 216 through the pour hole 220.
Any molten material may be employed that is convenient. Merely by
way of example, a magnesium-based material coated with ceramic
particles may be used for the internal insert component 224, and an
aluminum-based material such as an aluminum alloy may be used for
the molten material of the external part component.
[0049] Turning to FIG. 3B, the plunger 218 may be urged through the
sleeve 216, thereby forcing the molten material out of the sleeve
216, through the runner 222, and into the mold cavity 236. In one
example approach, the plunger 218 injects the molten material into
the mold cavity 236 in a two-stage process where the plunger 218
initially moves in a first stage at a relatively slow first speed
as the molten material is moved through the sleeve 216 and into the
runner 222. In a second stage, the plunger 218 injects the molten
material into the mold cavity 236 at increased pressure, which may
be imparted to the molten material by an increase in speed and/or
force of the plunger 218 as it moves through the sleeve 218.
[0050] Upon injection of the molten material into the mold cavity
236, the molten material may be cooled, e.g., by way of cooling
channels 228. Additionally, the locating pins 226 may be disposed
adjacent to one or more of the cooling channels 228, or be provided
with features internal to the locating pin(s) 226 that facilitate
cooling within the mold cavity 236. Moreover, cooling features of
the locating pins 226 may facilitate cooling that is focused on the
internal insert component 224, thereby allowing enhanced cooling of
the composite part from the inside as it is formed. As will be
described further below, enhanced cooling (particularly adjacent a
particle-rich region or interface between an internal insert
component and external part component) may allow not only faster
cycle times due to overall faster cooling, but also enhanced
material properties resulting from reductions in average grain size
of the formed part. Enhanced cooling may provide a directed cooling
path to the internal insert component 224 or regions thereof, e.g.,
by way of locating pin(s) such as locating pin 226 or other
examples provided below.
[0051] Referring now to FIG. 3C, upon solidification of the molten
material, the composite part 236' has been substantially formed
from the internal insert component 224 and the solidified molten
material surrounding at least a portion of the internal insert
component 224. Additionally, a flashing 222' may have been formed
during the solidification process, resulting from molten material
which solidified within the runner 222. Once the molten material is
solidified within the mold cavity 236, the movable ejector half 202
of the tool 200 may be moved away from the stationary half 204,
exposing the solidified part 236'. The ejector pin(s) 130 may urge
the solidified part out of the ejector half 202 of the tool, as
seen in FIG. 3D. For example, the ejector plate 232 may slide
laterally with respect to the support plate 214, thereby moving the
ejected pin(s) 230 and forcing the composite part 236' out of the
tool 200. The flashing 222' may be subsequently removed from the
composite part 236' and recycled. Moreover, any additional
finishing steps, e.g., machining, grinding, polishing, may be
performed on the composite part 236' to remove additional flashing
(not shown in FIG. 3D) or other portions of the composite part 236'
that may be undesirable.
[0052] Turning now to FIGS. 4A-4C, an exemplary internal insert
component comprising separate halves 324a, 324b (collectively,
internal insert component 324) is illustrated. The two halves 324a,
324b may be assembled together and placed within a mold cavity for
forming a composite part 236' as described above. The internal
insert 324 may also have at least a portion of an outer surface
thereof coated with certain types of particles 340. As will be
described further below, the particles 340 may enhance bonding of
the internal insert component 324 and the molten material used to
form the external part component of the composite part. While the
internal insert component 324 of FIGS. 4A-4C is illustrated as
being generally hollow and rectangular, in other approaches a solid
insert or inserts of other shapes may be employed. Hollow inserts
will likely be favored in applications that are focused on reducing
the weight of the composite part.
[0053] The two halves 324a, 324b may initially be assembled
together, as best seen in the perspective sectional view of FIG.
4B. A coating of at least a portion of an outer surface of one or
both halves 324a, 324b may occur prior to or after assembly of the
two halves 324a, 324b. Once the internal insert component 324 is
assembled and the particles 340 are applied thereto, the internal
insert component 324 may be placed within a mold cavity defined by
mold portions 306, 308 (see FIG. 4C). While the preceding
description of the internal insert component 324 describes a
two-piece insert, it is certainly possible for the insert to be a
one-piece insert or to have more than two pieces.
[0054] In some examples, one or more locating pins may be used to
position an internal insert component within a mold cavity. Example
locating pins will now be described in further detail, referring to
FIGS. 5A-5G.
[0055] As shown in FIGS. 5A and 5B, in one example approach, a
locating pin 426a may be cast-in to the resulting composite part
436 so that it becomes part of the resulting composite part. The
locating pin 426a may initially be cast into or pressed into an
internal insert component 424 (comprising halves 424a, 424b, as
shown in FIG. 5A, with the locating pin 426a being shown disposed
in the half 424b in FIG. 5B). As molten material introduced into
the mold cavity cools, solidifying the molten material and
permanently bonding to the internal insert component 424, the
cast-in locating pin 426a may also become permanently bonded with
the solidified external part component 436. An example of a cast-in
locating pin 426a is shown in section in FIG. 5B, where the cast-in
locating pin has become part of the resulting composite part and
may be made of an aluminum-based material suitable in composition
to that of the molten material.
[0056] In another example illustrated in FIG. 5A, a locating pin
426b may be permanently installed in the mold. Accordingly, the
locating pin 426b does not become part of the resulting composite
part. An example of the permanent support pin 426b is shown in
further detail in FIG. 5E. The support pin 426b is permanently
joined or fixed within the die 408, and extends into the mold
cavity to support the internal insert component 424a. Accordingly,
molten material does not permanently join with the locating pin
426b, but rather forms the composite part by surrounding the
internal insert component 424a without permanently bonding with the
molten material forming the external part component 436.
[0057] As mentioned above, locating pin(s) used to position an
internal insert component within a mold cavity may also facilitate
cooling within the mold cavity. For example, locating pins may
provide cooling of the molten material introduced to the cavity,
the internal insert component, a boundary region between the molten
material and the internal insert component, or any
combination/sub-combination of the three. In this manner, bonding
of the molten material introduced to the mold cavity around the
internal insert component may be enhanced by allowing enhanced
control of temperatures within the mold cavity, especially in a
boundary region between the internal insert component and the
molten material of the external part component. As noted above,
enhanced cooling (such as by way of the various example approaches
adjacent a particle-rich region or interface between an internal
insert component and external part component described below) may
allow faster cycle times due to overall faster cooling. Moreover,
reductions in average grain size of the formed part may also be
achieved by way of the faster cooling in the particle-rich and/or
interface region. More specifically, in one example average grain
size was reduced from an average of 78.times.52 microns in a
traditional casting process to an average of 37.times.32 microns
(by averaging measured boundaries of grains in a two-dimensional
micrograph or photo) using the faster cooling methodologies where
cooling is performed adjacent the particle-rich or interface
region.
[0058] Turning now to FIG. 5C, one example of a locating pin
providing cooling within the mold cavity is illustrated. A mold
cavity defined in part by a mold 408 may have a locating pin 426b
permanently installed within the mold, similar to the example
discussed above in FIG. 5E. In the example shown in FIG. 5C,
however, a cooling channel 428 passes through the mold 408 adjacent
an end of the locating pin 424b. As such, the locating pin 424b is
in contact with and removes heat from the internal insert component
424a and provides it to fluid flowing through the cooling channel
via conduction cooling such that it cools the internal insert
component 424a and/or external part component 436.
[0059] Referring now to FIG. 5D, another support pin with a cooling
feature is illustrated. Locating pin 426c is hollow and defines an
internal space that receives a phase change material (PCM) 450 that
is configured to absorb heat by way of phase changes of the PCM
450. For example, heat may be absorbed through the locating pin
426c by way of the PCM 450 changing from a solid phase to a liquid
phase. Heat may be stored in the PCM 450 and transferred to the
mold 408, thereby conducting heat away from the molten material as
it cools to form the external part component 436. Moreover, heat
conduction may be enhanced by providing cooling channels in the
mold 408, e.g., similar to cooling channel 428 described above in
conjunction with FIG. 5C. Example phase change materials that may
be used as PCM 450 may include, but are not limited to:
[0060] sodium sulfate (Na.sub.2SO.sub.4*10H.sub.2O);
[0061] NaCl*Na.sub.2SO.sub.4*10H.sub.2O; or
[0062] Na.sub.2SiO.sub.3*5H.sub.2O.
[0063] Turning now to FIG. 5F, another example locating pin 426d is
shown. Locating pin 426d may have a liquid cooling passage 452
defined therein to provide enhanced cooling of a mold cavity.
Liquid cooling passage 452 may receive coolant from or otherwise be
in fluid communication with other cooling passages of the mold 408,
e.g., cooling passage 428 described above. Alternatively, the
liquid cooling passage 452 may be a generally separate cooling
circuit from other cooling passages of the mold 408. Support pin
426d conducts heat away from the internal insert component 424 via
the coolant flow through the liquid cooling passage 452.
[0064] Referring now to FIG. 5G, another locating pin 426e is
illustrated. Locating pin 426e includes both a phase change
material (PCM) 450', as well as a liquid cooling passage 452'. By
combining PCM 450' with a liquid cooling channel 452', cooling of
the mold cavity may be further enhanced. It should be appreciated
that in each of the embodiments shown in FIGS. 5C-D and 5F-G, the
support pins both support the internal insert component, as well as
help control the temperature of the internal insert component as
the molten material of the external part component is cast and
solidifies around it.
[0065] As noted above, locating pins may be used to support and/or
provide targeting cooling with respect to an internal insert
component. Referring now to FIG. 5H, in examples where locating pin
426a is cast-in to the composite part, the completed composite part
may have the cast-in locating pin 426a protruding from the external
part component 436, the completed composite part is illustrated
with the locating pin 426a protruding from within the external part
component 436 of the composite part. The locating pin 426a may be
made of an aluminum-based material suitable in composition to that
of the molten material that forms the external part component 436
about the internal insert component 424b (not shown in FIG.
5H).
[0066] By contrast, in examples where a locating pin 426b is
permanently installed in the mold (e.g., as shown in FIG. 5E) and
the locating pin 426b does not become part of the resulting
composite part, the locating pin 426b may leave a gap or void in
the external part component surrounding the internal insert
component, exposing a portion of the internal insert component
within. More specifically, in the example of FIG. 5E, the permanent
support pin 426b extends into the mold cavity to support the
internal insert component 424a. Molten material does not
permanently join with the locating pin 426b, as noted above, but
rather forms the composite part by surrounding the internal insert
component 424a around the locating pin 426b. Upon removal of the
part from the mold, a gap or void 427 is left in the external part
component 436 surrounding the internal insert component 424a. As a
result, the internal insert component 424a is partially exposed
where the locating pin 426b had contacted the internal insert
component 424a to support the internal insert component 424a within
the mold.
Composite Part
[0067] Turning now to FIGS. 6A and 6B, an example composite part is
illustrated. The composite part is shown in a cutaway view to
illustrate an internal insert component 524 that defines a
generally cylindrical shape, and is surrounded by an external part
component 536. Particles applied to a surface of the internal
insert component 524 may generally disperse throughout a boundary
region located between the external part component 536 and the
internal insert component 524. In this manner, a particle-rich
region I may be formed that at least partially surrounds the
internal insert component 524. According to the embodiment where
the internal insert component 524 is made of a magnesium-based
material and is coated with ceramic particles and the exterior part
component 536 is made of an aluminum-based material, the
particle-rich region I includes an aluminum/magnesium intermetallic
interface with ceramic particles for enhanced bonding. More
generally, an intermetallic interface may be formed from three
materials: the material comprising the external part component
(e.g., external part component 536), the internal insert component
(e.g., internal insert component 524), and the particles. The
particle-rich region I can certainly vary in terms of thickness and
composition, but according to one example, it has a thickness of
approximately 20 .mu.m-180 .mu.m, inclusive, and even more
preferably a thickness of about 40 .mu.m-120 .mu.m, inclusive.
[0068] A concentration of the particles may form a gradient through
the material, e.g., where they are more concentrated in a portion
of the particle-rich region closest to the insert, and less
concentrated in a portion of the particle-rich region that is
closest to the external part. However, one potential advantage of
using an internal insert component 524 that is pre-coated with
particles is that, after solidification of the molten metal of the
external part component 536, the particle-rich region I generally
exhibits a more homogeneous distribution of particles which in turn
can promote a more even distribution of nucleation sites, better
micro-structure refinement, dislocation pinning, and increased bond
strength in general.
[0069] In one example, the internal insert component 524 is
initially coated with approximately 15% by weight particles on an
outer surface of the internal insert component 524. With a
substantially homogeneous distribution of the particles on the
surface, a reduced grain size of the resulting particle-rich region
I may be achieved. In one example, grain size in the particle-rich
region may be reduced by 30% to 50% in an example where the
particles have a substantially homogeneous distribution on the
portion(s) of the outer surface of the internal insert component
524 that is coated, as compared with comparable materials or alloys
having poor particle-dispersion homogeneity or formed without
particles. In some previous methods of introducing particles in
casting, clustering of the particles together has resulted, which
may defeat the purpose of using the particles as it produces
regions with non-uniform microstructure (and, as a result,
deteriorated mechanical and bonding properties). In one example of
a substantially homogeneous distribution of particles, a
measurement by weight percentage of the particle distribution does
not vary more than_12% anywhere on the portion(s) of the outer
surface of the internal insert component 524 that is coated with
particles. For example, in an embodiment where particles have a 15%
by weight distribution on the surface of the internal insert
component 524 as noted above, a substantially homogeneous
distribution means that a percentage by weight of the particles in
the portion(s) of the outer surface of the internal insert
component 524 that are coated may vary from 13.2% by weight to
16.8% by weight.
[0070] Referring now to FIGS. 7A-7D, another example of internal
insert component 624 and external part component 636 is
illustrated. The internal insert component 624 may be hollow and
formed of magnesium (although other materials could be used
instead), and comprises a main body portion 624a and cap portion
624b. The main body portion 624a and cap portion 624b may be
assembled together to form the internal insert component 624.
Portions of one or both of the cap portion 624b and main body
portion 624a may be coated with particles such as any of the
examples described above. The assembled internal insert component
624 may then be placed into a mold (not shown in FIGS. 7A-7D), and
an external part component 636 may be formed about the internal
insert component 624 by injecting molten aluminum material into the
mold cavity, e.g., by a high-pressure die cast process.
Accordingly, a particle-rich region may be provided between the
internal insert component 624 and external part component 636.
Method of Producing Composite Part
[0071] Turning now to FIG. 8, an example process 800 is illustrated
for forming a composite part having an internal insert component
and an external part component. Process 800 may begin at block 810,
where an internal insert component is positioned in a mold cavity.
For example, as described above an internal insert component 224,
324, 424, 524, or 624 may be positioned within a mold. In some
examples, the internal insert component may be provided with a
coating on at least a portion of an outer surface, in order to
facilitate the formation of a particle-rich region. While the
internal insert component may be formed of any material that is
convenient, example materials include magnesium-based alloys and
other materials. Process 800 may then proceed to block 820.
[0072] At block 820, a molten material may be cast about the
internal insert component. For example, as described above a molten
aluminum-based material may be introduced to a mold cavity
containing the internal insert component. Any number of different
casting processes may be used including, but not limited to,
gravity casting, low pressure casting and high pressure die
casting. According to some embodiments, high pressure die casting
of aluminum alloys is preferred.
[0073] Proceeding to block 830, the internal insert component may
be cooled as the molten material is cast about the internal insert
component. Cooling may be facilitated, for example, using locating
or support pin(s) 226, 326, 426 as described above. Consistent with
the examples provided, cooling using the locating pin(s) 226, 326,
426 may be facilitated with a phase-change material, by way of a
solid locating pin conducting heat from the mold, and/or with
liquid cooling channels within the locating pin, merely as
examples. Process 800 may then proceed to block 840.
[0074] At block 840, the molten material may be solidified to form
an external part component disposed about the internal insert
component. Molten material may be cooled or solidified using
cooling features in the mold or locating pin(s). Moreover, as
described above, in some approaches a particle-rich region may be
formed between the internal insert component and external part
component, e.g., by dispersion of particles applied in initially in
a coating to a portion of the internal insert component, as
described above.
[0075] It is to be understood that the foregoing description is not
a definition of the invention, but is a description of one or more
exemplary illustrations of the invention. The invention is not
limited to the particular example(s) disclosed herein, but rather
is defined solely by the claims below. Furthermore, the statements
contained in the foregoing description relate to particular
exemplary illustrations and are not to be construed as limitations
on the scope of the invention or on the definition of terms used in
the claims, except where a term or phrase is expressly defined
above. Various other examples and various changes and modifications
to the disclosed embodiment(s) will become apparent to those
skilled in the art. All such other embodiments, changes, and
modifications are intended to come within the scope of the appended
claims.
[0076] As used in this specification and claims, the terms "for
example," "e.g.," "for instance," "such as," and "like," and the
verbs "comprising," "having," "including," and their other verb
forms, when used in conjunction with a listing of one or more
components or other items, are each to be construed as open-ended,
meaning that that the listing is not to be considered as excluding
other, additional components or items. Other terms are to be
construed using their broadest reasonable meaning unless they are
used in a context that requires a different interpretation.
* * * * *