U.S. patent application number 14/682411 was filed with the patent office on 2016-10-13 for die-casting system with a refractory metal alloy surface.
The applicant listed for this patent is UNITED TECHNOLOGIES CORPORATION. Invention is credited to TAN YONG SHENG ANDREW, LIM YUAN KWANG, MUHAMMAD AZZLI BIN MAHMOOD, LOH YAN SENG.
Application Number | 20160296997 14/682411 |
Document ID | / |
Family ID | 57111224 |
Filed Date | 2016-10-13 |
United States Patent
Application |
20160296997 |
Kind Code |
A1 |
KWANG; LIM YUAN ; et
al. |
October 13, 2016 |
DIE-CASTING SYSTEM WITH A REFRACTORY METAL ALLOY SURFACE
Abstract
A die-casting mold, includes a die insert including a mold
surface with a refractory metal alloy layer and a method of
manufacturing a die-casting mold, including machining a mold
surface of a die insert such that the mold surface is a near net
shape with respect to a workpiece and applying a refractory metal
alloy layer onto the die insert.
Inventors: |
KWANG; LIM YUAN; (Singapore,
SG) ; ANDREW; TAN YONG SHENG; (Singapore, SG)
; MAHMOOD; MUHAMMAD AZZLI BIN; (Singapore, SG) ;
SENG; LOH YAN; (Singapore, SG) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNITED TECHNOLOGIES CORPORATION |
HARTFORD |
CT |
US |
|
|
Family ID: |
57111224 |
Appl. No.: |
14/682411 |
Filed: |
April 9, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22D 17/2209 20130101;
B22F 2009/041 20130101; C22C 27/00 20130101; B23K 26/144 20151001;
C22C 1/045 20130101; B23K 26/342 20151001; B22F 3/1055 20130101;
Y02P 10/295 20151101; B22C 9/18 20130101; B22F 7/08 20130101; B22C
3/00 20130101; B22C 9/061 20130101; Y02P 10/25 20151101 |
International
Class: |
B22C 9/18 20060101
B22C009/18; B22C 3/00 20060101 B22C003/00; B22C 9/06 20060101
B22C009/06; B22D 17/22 20060101 B22D017/22 |
Claims
1. A die-casting mold, comprising: a die insert including a near
net shape mold surface with a refractory metal alloy layer, wherein
the refractory metal alloy layer is manufactured from a
compositionally homogeneous powder mixture that is utilized in a
laser cladding operation to produce the refractory metal alloy
layer.
2. The mold as recited in claim 1, wherein the mold surface is
undersized with respect to a workpiece.
3. The mold as recited in claim 2, wherein the refractory metal
alloy layer is sized to form the workpiece.
4. The mold as recited in claim 1, wherein the refractory metal
alloy layer includes Anviloy.RTM..
5. The mold as recited in claim 1, wherein the refractory metal
alloy layer includes Tungsten (W).
6. The mold as recited in claim 1, wherein the refractory metal
alloy layer is W90Ni4Mo4Fe2.
7. The mold as recited in claim 1, wherein the refractory metal
alloy layer is manufactured from a compositionally homogeneous
powder mixture that is utilized in a laser cladding operation to
produce the refractory metal alloy layer.
8. The mold as recited in claim 7, wherein the compositionally
homogeneous powder mixture includes tungsten (W) powder of less
than about 44 microns particle size and other powders of less than
about 74 microns particle size.
9. The mold as recited in claim 8, wherein the other powders
include Nickel (Ni), Molybdenum (Mo,) and Iron (Fe) powder.
10. The mold as recited in claim 1, wherein the refractory metal
alloy layer is about 0.010'' in thickness.
11. The mold as recited in claim 1, further comprising a die
housing, the die insert at least partially receivable into the die
housing.
12. A method of manufacturing a die-casting mold, comprising:
machining a mold surface of a die insert such that the mold surface
is undersized with respect to a desired near net shape with respect
to a workpiece; applying a refractory metal alloy layer onto the
die insert to form a near net shape wherein the refractory metal
alloy layer is manufactured from a compositionally homogeneous
powder mixture that is utilized in a laser cladding operation to
produce the refractory metal alloy layer; and performing a
post-clad machining operation to finalize the near net shape mold
surface with respect to the workpiece.
13. The method as recited in claim 12, wherein the die insert is
manufactured of steel.
14-15. (canceled)
16. The method as recited in claim 12, further comprising ball
milling a powder mixture to form the compositionally homogeneous
powder mixture.
17. The method as recited in claim 12, further comprising ball
milling a powder mixture including tungsten (W) powder of less than
about 44 microns particle size, and other powders of less than
about 74 microns particle size to form the compositionally
homogeneous powder mixture.
18. The method as recited in claim 17, wherein the other powders
include Nickel (Ni), Molybdenum (Mo,) and Iron (Fe) powder.
19. The method as recited in claim 12, wherein a powder mixture
forming the compositionally homogeneous powder mixture includes
tungsten (W) powder of about 325M.
20. The method as recited in claim 19, wherein the powder mixture
includes other powders of about 200M.
21. The mold as recited in claim 1, wherein a hardness is
controlled by a fine microstructure in the refractory alloy
layer.
22. The method as recited in claim 12, further comprising adjusting
a rate of solidification via the laser cladding operation to
control the hardness by control of a fine microstructure in the
refractory alloy layer.
Description
BACKGROUND
[0001] The present disclosure relates to die-casting and, more
particularly, to a die-casting mold with an undersized cavity
pattern with a refractory metal alloy layer.
[0002] A die-casting mold typically contains steel die cavity
inserts within a steel housing. Some die-casting molds utilize
cavity inserts manufactured of relatively thick layer of refractory
metals backed by a steel plate bolted in countersunk manner.
Although effective, the refractory metal is necessarily of a
thickness to allow the mold pattern to be machined into the
refractory metal, hence rendering little practical cost savings.
This may also be relatively expensive, as refractory metal alloys,
and ceramics, may be difficult to machine. This typically may
result in a long fabrication lead-times.
SUMMARY
[0003] A die-casting mold, according to one disclosed non-limiting
embodiment of the present disclosure can include a die insert
including a mold surface with a refractory metal alloy layer.
[0004] A further embodiment of the present disclosure may include,
wherein the mold surface is undersized with respect to a
workpiece.
[0005] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the refractory metal
alloy layer is sized to form the workpiece.
[0006] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the refractory metal
alloy layer includes Anviloy.
[0007] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the refractory metal
alloy layer includes Tungsten (W).
[0008] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the refractory metal
alloy layer is W90Ni4Mo4Fe2.
[0009] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the refractory metal
alloy layer is manufactured from a compositionally homogeneous
powder mixture that is utilized in a laser cladding operation to
produce the refractory metal alloy layer.
[0010] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the compositionally
homogeneous powder mixture includes tungsten (W) powder of less
than about 44 microns particle size and other powders of less than
about 74 microns particle size.
[0011] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the other powders
include Nickel (Ni), Molybdenum (Mo,) and Iron (Fe) powder.
[0012] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the refractory metal
alloy layer is about 0.010'' in thickness.
[0013] A further embodiment of any of the foregoing embodiments of
the present disclosure may include a die housing, the die insert at
least partially receivable into the die housing.
[0014] A method of manufacturing a die-casting mold, according to
another disclosed non-limiting embodiment of the present disclosure
can include machining a mold surface of a die insert such that the
mold surface is a near net shape with respect to a workpiece; and
applying a refractory metal alloy layer onto the die insert.
[0015] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the die insert is
manufactured of steel.
[0016] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein applying the refractory
metal alloy layer includes a laser cladding operation with a
compositionally homogeneous powder mixture.
[0017] A further embodiment of any of the foregoing embodiments of
the present disclosure may include performing a post-clad machining
operation to finalize the mold surface with respect to the
workpiece.
[0018] A further embodiment of any of the foregoing embodiments of
the present disclosure may include ball milling a powder mixture to
form the compositionally homogeneous powder mixture.
[0019] A further embodiment of any of the foregoing embodiments of
the present disclosure may include ball milling a powder mixture
including tungsten (W) powder of less than about 44 microns
particle size, and other powders of less than about 74 microns
particle size to form the compositionally homogeneous powder
mixture.
[0020] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the other powders
include Nickel (Ni), Molybdenum (Mo,) and Iron (Fe) powder.
[0021] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein a powder mixture
forming the compositionally homogeneous powder mixture includes
tungsten (W) powder of about 325M.
[0022] A further embodiment of any of the foregoing embodiments of
the present disclosure may include, wherein the powder mixture
includes other powders of about 200M.
[0023] The foregoing features and elements may be combined in
various combinations without exclusivity, unless expressly
indicated otherwise. These features and elements as well as the
operation thereof will become more apparent in light of the
following description and the accompanying drawings. It should be
understood, however, the following description and drawings are
intended to be exemplary in nature and non-limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Various features will become apparent to those skilled in
the art from the following detailed description of the disclosed
non-limiting embodiment. The drawings that accompany the detailed
description can be briefly described as follows:
[0025] FIG. 1 is a schematic cross-sectional view of a die casting
mold;
[0026] FIG. 2 is a block diagram illustrating a method to
manufacture the die-casting mold;
[0027] FIG. 3 is a schematic cross-sectional view of a laser
cladding process for the die casting mold to apply a refractory
metal alloy layer;
[0028] FIG. 4 is a schematic cross-sectional view of thermal
distribution provided by the die casting mold;
[0029] FIG. 5 is a block diagram illustrating a method for powder
processing to form a compositionally homogeneous powder mixture
feedstock for the refractory metal alloy layer of the die-casting
method of FIG. 2.
DETAILED DESCRIPTION
[0030] FIG. 1 schematically illustrates a die-casting mold 20.
Although only one side of the die-casting mold 20 is illustrated,
the other side will be generally equivalent. The die-casting mold
20 includes a die housing 22 and a die insert 24 at least partially
received into the die housing 22. The die insert 24 includes a mold
surface 26 with a refractory metal alloy layer 28. That is, the
undersized aspect of the die insert 24 is brought up to proper size
to form the workpiece by the refractory metal alloy layer 28. In
one disclosed example, the die housing 22 is manufactured of 4340
steel, the die insert 24 may be manufactured of tool steel, and the
refractory metal alloy layer 28 may be manufactured of a relatively
thin Anviloy.RTM., tungsten alloy, molybdenum or other refractory
metal alloy that forms a final mold surface layer 30 and is about
0.010'' in thickness. Anviloy.RTM. is a machinable tungsten-based
material developed primarily for die-casting, aluminum permanent
mold, and difficult extrusions.
[0031] With reference to FIG. 2, a method 100 to manufacture the
die insert 24 initially includes machining the mold surface 26. The
mold surface 26 is first undersized--with respect to the desired
final dimensions of a workpiece to be die-cast--but close to near
net shape (step 102). Next, a compositionally homogeneous powder
mixture feedstock for the refractory metal alloy layer 24 is
manufactured (step 104) as further described below.
[0032] Next, the compositionally homogeneous powder mixture
feedstock is utilized in a laser cladding operation (step 106) to
produce the refractory metal alloy layer 28 on the die insert 24.
In one example, Anviloy.RTM. type powder may be utilized, but the
powder is not limited to Anviloy.RTM. or tungsten alloy powders as
the choice of powder may be achieved to select the application and
properties desired. The laser process facilitates the rapid
solidification of the refractory metal alloy layer 28 onto the mold
surface 26 with metallurgical bonding for the production of a high
hardness.
[0033] In one embodiment, the compositionally homogeneous powder
mixture feedstock is communicated through cladding nozzles onto the
mold surface 26 and laser beam rastered onto the powder to create a
melt pool that is allowed to solidify rapidly under a protective
Argon (Ar) atmosphere (FIG. 3). The refractory metal alloy layer 28
then solidifies onto the mold surface 26.
[0034] Next, post-clad machining is performed (step 108) to
finalize the desired mold surface layer 30. Minimal post-clad
machining results in a die surface of a desired roughness to
perform the die cast. In general, a die insert with high hardness,
toughness and tunable thermal conductivity is conducive to prolong
tool life that readily produces acceptable die castings with low
porosity.
[0035] Thus, the relatively thin layer of the refractory metal
alloy layer 28 has a relatively high thermal conductivity (region
of .about.128 W/m-K) fabricated onto a relatively lower thermal
conductivity (an order of magnitude lower) steel substrate surface
(with minimal or no post clad machining required). This allows the
die insert 24 to advantageously distribute the heat on the surface
yet be durable (FIG. 4.) The laser surface engineered also
facilitates repair of the die insert 24 since only the mold surface
26 is treated with the refractory metal alloy layer 28. Further,
the die insert 24 steel substrate affords the toughness to
withstand the punishing cyclic rigors of the die cast process that
repeatedly and dynamically squeezes the rapidly solidifying molten
mass of the high temperature superalloy workpiece within the die
insert 24.
[0036] With reference to FIG. 5, a method 200 for powder processing
to form the compositionally homogeneous powder mixture feedstock
for the subsequent laser melting initially includes selection of a
Tungsten (W), Nickel (Ni), Molybdenum (Mo) and Iron (Fe) powder
(steps 202, 204) prior to mixture thereof (step 206).
[0037] The tungsten alloy powder provides an extremely high melting
range of about 2597-6170.degree. F. and high thermal conductivity
of about 128 W/m-K to withstand the molten superalloy (reported
2300-2437.degree. F. for IN718). The tungsten alloy powder for
superalloy die-cast application can be of a composition that is
equivalent, or similar, to Anviloy, i.e., W90Ni4Mo4Fe2. In one
example, the tungsten (W) is about 90% by weight of the
mixture.
[0038] The mixture of Tungsten (W), Nickel (Ni), Molybdenum (Mo),
and Iron (Fe) powders include a distribution of particle sizes with
the lower weight percent elements having coarser particle size
distributions, whilst tungsten (W) is at finer particle size
distribution. Hence, in one example, -325M (-325 mesh equivalent to
less than 44 microns particle size) of tungsten (W) powder, and
-200M (equivalent to less than 74 microns particle size) of the
other powder is utilized. That is, a micron particle size ratio of
the tungsten (W) powder to the other powders is about 44:74. In one
example, the tungsten (W) is about 80%-90% by weight of the mixed
powder. In another example, the tungsten (W) is about 90% by weight
of the mixed powder, the Nickel (Ni) is about 4%, the Molybdenum
(Mo) is about 4%, and the Iron (Fe) is about 2%.
[0039] The mixed powder is then ball milled (step 208) such as via
a tubular blender, to produce the compositionally homogeneous
powder mixture feedstock with effective powder distribution and
chemical homogeneity for subsequent processing (step 210, 212). The
ball milling ensures homogeneity in the mechanically alloyed powder
so as to produce a homogenous powder for the laser melting onto the
steel substrate (step 106; FIG. 2). It should be appreciated that
various powder mixing may alternatively or additionally be
provided.
[0040] The method 100 for manufacture of the die insert 24
advantageously reduces cost as the fabrication of an entire die
insert is not manufactured from refractory alloys, as well as
permits versatility in the die insert fabrication. The method 200
for powder processing to form the compositionally homogeneous
powder mixture feedstock permits the adjustment of the powder
composition, so as to produce a specifically tailored physical
surface to include tunable thermal conductivity. In principle, a
high thermally conductivity material experiences less thermal
strain on the material and prolong die life. Coupled with a high
melting point alloy, it is then possible to die cast high
temperature superalloys without chemical alloying the surfaces. The
laser melting process also allows adjustment as to the rate of
solidification to control the hardness via control of fine
microstructure in the refractory alloy layer. Whilst high thermal
conductivity favors less thermal strain and hence longer die life
through less thermal fatigue cracks, the high thermal conductivity
also negatively impacts die cast-ability of superalloys with a too
rapid freezing rate. Hence, a relatively thin layer of refractory
metal is preferred
[0041] The use of the terms "a," "an," "the," and similar
references in the context of description (especially in the context
of the following claims) are to be construed to cover both the
singular and the plural, unless otherwise indicated herein or
specifically contradicted by context. The modifier "about" used in
connection with a quantity is inclusive of the stated value and has
the meaning dictated by the context (e.g., it includes the degree
of error associated with measurement of the particular quantity).
All ranges disclosed herein are inclusive of the endpoints, and the
endpoints are independently combinable with each other. It should
be appreciated that relative positional terms such as "forward,"
"aft," "upper," "lower," "above," "below," and the like are with
reference to the normal operational attitude of the vehicle and
should not be considered otherwise limiting.
[0042] Although the different non-limiting embodiments have
specific illustrated components, the embodiments of this invention
are not limited to those particular combinations. It is possible to
use some of the components or features from any of the non-limiting
embodiments in combination with features or components from any of
the other non-limiting embodiments.
[0043] It should be appreciated that like reference numerals
identify corresponding or similar elements throughout the several
drawings. It should also be appreciated that although a particular
component arrangement is disclosed in the illustrated embodiment,
other arrangements will benefit herefrom.
[0044] Although particular step sequences are shown, described, and
claimed, it should be understood that steps may be performed in any
order, separated or combined unless otherwise indicated and will
still benefit from the present disclosure.
[0045] The foregoing description is exemplary rather than defined
by the limitations within. Various non-limiting embodiments are
disclosed herein, however, one of ordinary skill in the art would
recognize that various modifications and variations in light of the
above teachings will fall within the scope of the appended claims.
It is therefore to be appreciated that within the scope of the
appended claims, the disclosure may be practiced other than as
specifically described. For that reason the appended claims should
be studied to determine true scope and content.
* * * * *