U.S. patent application number 10/983962 was filed with the patent office on 2005-07-21 for device and method for cooling a shot plug.
Invention is credited to Squires, Wayne F..
Application Number | 20050155738 10/983962 |
Document ID | / |
Family ID | 34590195 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050155738 |
Kind Code |
A1 |
Squires, Wayne F. |
July 21, 2005 |
Device and method for cooling a shot plug
Abstract
The invention is accomplished by a shot block that is located
intermediate the die and the shot sleeve. Such a shot block
includes a body having mutually opposed first and second engagement
surfaces. The first engagement surface abuts the shot sleeve and
the second engagement surface abuts the die. A passage extends
longitudinally through the body and defines an opening at the first
engagement surface and an opening at the second engagement surface
for transmitting a molten or semi-molten metal charge under
pressure from the shot sleeve, through the passage, and into the
die cavity. A cooling channel within the body circulates a fluid
therethrough to absorb heat from the charge located within at least
a portion of said passage (i.e. the biscuit).
Inventors: |
Squires, Wayne F.; (Rocky
River, OH) |
Correspondence
Address: |
MCDONALD HOPKINS CO., LPA
2100 BANK ONE CENTER
600 SUPERIOR AVENUE, E.
CLEVELAND
OH
44114-2653
US
|
Family ID: |
34590195 |
Appl. No.: |
10/983962 |
Filed: |
November 8, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60517832 |
Nov 6, 2003 |
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Current U.S.
Class: |
164/312 ;
164/113 |
Current CPC
Class: |
B22D 17/08 20130101;
B22D 17/2038 20130101; B22D 17/2023 20130101 |
Class at
Publication: |
164/312 ;
164/113 |
International
Class: |
B22D 017/08 |
Claims
Having thus described the invention, I claim:
1. A die casting machine for creating a die cast component from a
molten or semi-molten metal charge, said die casting machine
comprising: a first die and a second die configured for confronting
engagement with one another along a separation surface and together
defining at least one die cavity therebetween; a shot block having
a passage extending therethrough, said passage in fluid
communication with said die cavity for transmitting a molten or
semi-molten metal charge to said die cavity; a cooling channel
within said body for circulating a fluid therethrough to absorb
heat from said charge located within at least a portion of said
shot block passage; a shot sleeve having a passage, said shot
sleeve abutting said shot block wherein said shot sleeve passage is
in fluid communication with said shot block passage for
transmitting said charge to said shot block passage; a plunger
disposed within said shot sleeve passage for forcing said charge
through said shot sleeve; and wherein a cross-section of said shot
sleeve passage is substantially equal to a cross-section of said
shot block passage so that said plunger is capable of entering said
shot block passage.
2. The die casting machine of claim 2 wherein said shot block
passage is substantially cylindrical.
3. The die casting machine of claim 3 wherein said shot sleeve
passage is substantially cylindrical.
4. The die casting machine of claim 3 wherein said plunger has a
cross section substantially equal to the cross-section of said shot
sleeve passage.
5. The die casting machine of claim 1 wherein said cooling channel
is located radially outwardly from said shot block passage.
6. The die casting machine of claim 5 wherein said cooling channel
extends longitudinally within said shot block.
7. The die casting machine of claim 5 wherein said cooling channel
extends at least partially circumferentially about said shot block
passage.
8. A die casting machine for creating a die cast component from a
molten or semi-molten metal charge; said die casting machine
comprising: a first die and a second die configured for confronting
engagement with one another along a separation surface and together
defining at least one die cavity therebetween; a shot block having
a generally cylindrical passage extending therethrough, said
passage in fluid communication with said die cavity for
transmitting a molten or semi-molten metal charge to said die
cavity, said passage having a diameter; a cooling channel within
said body for circulating a fluid therethrough to absorb heat from
said charge located within at least a portion of said passage; a
shot sleeve having a generally cylindrical passage with a diameter,
said shot sleeve abutting said shot block wherein said shot sleeve
passage is in fluid communication with said shot block passage for
transmitting said charge therethrough to said shot block passage; a
plunger disposed within said shot sleeve passage for forcing said
charge through said shot sleeve; and wherein the diameter of said
shot block passage is substantially equal to the diameter of said
shot sleeve passage so that said plunger is capable of entering
said shot block passage.
9. The die casting machine of claim 8 wherein said cooling channel
is located radially outwardly from said shot block passage.
10. The die casting machine of claim 9 wherein said cooling channel
extends longitudinally within said shot block.
11. The die casting machine of claim 10 wherein said cooling
channel extends at least partially circumferentially about said
shot block passage.
12. A shot block for use in a die casting machine wherein said shot
block provides fluid communication of a molten or semi-molten metal
charge between a shot sleeve and a die having a die cavity, the
shot block comprising: a body having mutually opposed first and
second engagement surfaces, said first engagement surface capable
of abutting engagement with a shot sleeve and said second
engagement surface capable of abutting engagement with a die having
a die cavity; a passage extending longitudinally through said body
and defining an opening at said first engagement surface and an
opening at said second engagement surface for transmitting a molten
or semi-molten metal charge under pressure through said passage; a
cooling channel within said body for circulating a fluid
therethrough to absorb heat from said charge located within at
least a portion of said passage.
13. The shot block of claim 12 wherein said passage is
substantially cylindrical.
14. The shot block of claim 12 wherein wherein said cooling channel
is located radially outwardly from said passage.
15. The shot block of claim 14 wherein said cooling channel extends
longitudinally within said shot block.
16. The shot block of claim 15 wherein said cooling channel extends
at least partially circumferentially about said passage.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of priority from U.S.
Provisional Patent Application No. 60/517,832 filed on Nov. 6,
2003.
FIELD OF THE INVENTION
[0002] The present invention relates to a method and apparatus for
die casting parts, and more particularly, to a method and apparatus
for die casting parts by cooling a shot plug or biscuit.
BACKGROUND
[0003] High-pressure die casting is an important process for
manufacturing high volume and low cost components. Examples from
the automotive industry include automatic transmission housings,
piston heads, and gear box components. In this process molten or
semi-molten metal (generally aluminum alloy) is injected at high
speed (around 50 to 100 m/s) and under very high pressures through
complex gate and runner systems and into a die.
[0004] In cold-chamber die casting, for which the present invention
is particularly suited, molten or semi-molten metal is injected
under pressure into hardened steel dies, often water-cooled. The
molten metal, held in a separate furnace, is transferred by a ladle
and poured into an extension tube, (generally called the shot
sleeve), projecting from the entry point to the die.
[0005] A conventional die casting machine typically includes a die
composed of a cover die half and an ejector die half. The cover die
half and the ejector die half mate with one another along a
separation surface and together define multiple die cavities. The
cover die half is stationary, while the ejector die half is movable
so that when a molten charge injected therein solidifies, the
ejector die half can then be moved apart from the cover die half so
that the solidified charge in each mold cavity can be removed.
[0006] Molten or semi-molten metal to be cast is charged into the
die cavities by a charging assembly that includes a pressure
cylinder or "shot sleeve" for receiving molten metal from an inlet,
a piston movable in the shot sleeve for forcing the molten metal
into the die cavities, and a shot block extending over the shot
sleeve and connected to the die. The molten metal from the shot
sleeve is supplied to the die cavities via passageways or "runners"
defined in the separation surface between the cover die half and
the ejector die half. Cooling flow passageways may be provided in
the shot block for cooling the shot sleeve and thereby indirectly
cooling the biscuit through the use of water, oil or other liquid
as the cooling medium.
[0007] The plunger moves along the shot sleeve and pushes the
molten metal through the shot sleeve and into the runner and die
cavity. This molten charge (more material than is required to fill
the casting) is used to force additional metal into the die cavity
to supplement alloy shrinkage that takes place during
solidification. Thus, in actual practice, the metal charge in the
shot sleeve (typically referred to as a "biscuit") will often still
be molten, or at least partially molten, when the metal in the die
cavities has completely solidified. The interconnected component
and biscuit must sufficiently cool so as to form a solidified metal
component consisting of the casting, runner, overflows, flash, and
biscuit--as it is when removed from a die casting die. Once the
metal in the mold cavities has solidified, the die halves are
separated from one another and the solidified castings are ejected
therefrom for further processing.
[0008] It is always desirable to shorten cycle times in the die
casting operation to improve efficiency and increase production.
And since the biscuit is typically the last component section to be
sufficiently cooled prior to removing the component from the die,
any increase in the cooling rate of the biscuit greatly influences
shorter cycle times. Generally, the time it takes the biscuit to
solidify sufficiently represents the constraining factor in
achieving shorter cycle times in 25% to 50% of commercial die
casting operations. Accordingly, there is a need in the art to
achieve shorter cycle times by increasing the cooling rate of the
biscuit before the die halves are separated.
[0009] The prior art has attempted to increase the cooling rate of
the biscuit with little success. As described above, cooling lines
have been provided in the shot block to dissipate heat from the end
portion of the shot sleeve. While these cooling lines do remove
some heat from the shot sleeve, often very little resultant cooling
effect is provided to the biscuit.
[0010] Most importantly, it has been realized that the constant
heating and cooling of the shot sleeve itself causes deformation or
bowing therein. Such shot sleeve deformation or bowing can have
damaging effects on the resultant die cast component.
[0011] Even during normal operation, a thin metal skin is often
created on the interior of the shot sleeve formed from residual
molten metal that cools and adheres to the shot sleeve passage.
During repeated operation, the bowing of the shot sleeve can cause
the plunger to scrape and break this skin which thereby creates
particle impurities in the molten charge that can cause nucleation
in the die cast component. As such, there is a need in the art to
improve the cooling effect on the biscuit while also preventing the
creating of particle impurities caused by the deformation or bowing
of the shot sleeve.
SUMMARY OF THE INVENTION
[0012] The present invention includes numerous advantages and
benefits over the prior art. Particularly, the present invention
utilizes a shot block that does not encompass the shot sleeve as
know in the prior art so that cooling effects provided by the shot
block act directly upon the biscuit rather than indirectly on the
biscuit through the shot sleeve. As such, improved cooling effects
on the biscuit are realized to reduce overall cycle time of the
casting operation. By reducing the length of the shot sleeve and
providing cooling grooves in the shot block, cycle times can be
reduced 10-15% and possible more.
[0013] The invention is accomplished by a shot block that is
located intermediate the die and the shot sleeve. Such a shot block
includes a body having mutually opposed first and second engagement
surfaces. The first engagement surface abuts the shot sleeve and
the second engagement surface abuts the die. A passage extends
longitudinally through the body and defines an opening at the first
engagement surface and an opening at the second engagement surface
for transmitting a molten or semi-molten metal charge under
pressure through the passage. A cooling channel within the body
circulates a fluid therethrough to absorb heat from the metal
charge located within at least a portion of the passage (i.e. the
biscuit).
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0014] Objects and advantages together with the operation of the
invention may be better understood by reference to the detailed
description taken in connection with the following illustrations,
wherein:
[0015] FIG. 1 is a cross-sectional view of a prior art cold-chamber
die casting operation showing the shot sleeve within the shot
block.
[0016] FIG. 2 is a cross-sectional view of the connection of FIG. 1
including drilled cooling lines in the shot block.
[0017] FIG. 3 is a cross-sectional view of the shot sleeve
connection of a cold-chamber die casting operation according to the
present invention.
[0018] FIG. 4 is a plan view of the shot block according to the
present invention.
[0019] FIG. 5 is a cross-sectional view of the shot block of FIG. 4
taken along line A-A.
[0020] FIG. 6 is a cross-sectional view of the shot block of FIG. 4
taken along line B-B.
DETAILED DESCRIPTION OF THE INVENTION
[0021] In a typical cold-chamber die casting operation as shown in
FIG. 1, molten metal is injected, under pressure, into hardened
steel dies, often water-cooled. The molten metal, held in a
separate furnace, is transferred by a ladle and poured into an
extension tube or shot sleeve 10 projecting from a shot block 12.
The molten metal is injected into a runner 14 formed by a runner
block 16 and is thereby forced into the cavity formed by the
dies.
[0022] Because the shot plug or biscuit 20 can be the determining
factor in the cycle time of many casting operations, FIG. 2
illustrates a known attempt to increase the cooling rate of the
shot sleeve 10 to thereby increase the cooling rate of the biscuit
20. Cooling lines 18 are formed in the shot block 12 and filled
with a cooling solution, often water, to assist in dissipating the
heat encountered by the shot sleeve 10. However, while this process
assists in cooling the shot sleeve 10, it appears to have little
effect on the rapid cooling of the biscuit 20 and does not generate
significant cycle time reductions. In other cases where waterlines
are not utilized, no significant increase in cooling effect on the
biscuit 20 is achieved.
[0023] The present invention utilizes a similar construction as
previously described. The present invention utilizes a construction
where the biscuit is directly cooled via the shot block. Thus, the
shot sleeve of the present invention does not extend within the
shot block thereby indirectly cooling the biscuit through the shot
sleeve as known in the prior art. Further, cooling channels or
troughs are formed in the cover shot block and filled with a
cooling solution, typically water, to dissipate heat from the
biscuit. Therefore, the shortened shot sleeve provides direct
cooling to the solidifying biscuit through the shot block via the
cooling troughs. Such a construction also prevents the possible
deformation or bowing of the shot sleeve, as described above, and
the associated disadvantages related thereto.
[0024] With particular reference to FIG. 3, a die casting machine
for creating a die cast component from a molten or semi-molten
metal charge according to the present invention, generally
designated as 40, comprises a die 42, a shot block 44, a shot
sleeve 46, and a plunger 48.
[0025] Although any die configuration could be provide, generally a
first die and a second die are configured for confronting
engagement with one another along a separation surface and together
define at least one die cavity therebetween. This die cavity is
typically accessible through a runner 50. The shot sleeve 46
provides the molten or semi-molten charge to the die casting
machine 40 by use of a plunger 48 or similar device. With a metal
charge in the shot sleeve 46, the plunger 48 forces the charge
through the shot block 44 and into the die cavity.
[0026] The shot sleeve 46 has a passage 52 therethrough for
transmitting the metal charge. The shot sleeve 46 abuts the shot
block 44 wherein the shot sleeve passage is in fluid communication
with the shot block passage for transmitting the metal charge to
the shot block passage. As shown in FIGS. 1 and 2, the prior art
inserts the shot sleeve into the shot block for transmittal of the
molten metal charge to the die cavities
[0027] The shot block 44 is located intermediate the die and the
shot sleeve 46. The shot block 44 includes a body 51 having
mutually opposed first and second engagement surfaces 53, 55. The
first engagement surface 53 abuts the shot sleeve and the second
engagement surface 55 abuts the die. A passage 54 extends
longitudinally through the body 51 and defines an opening 57 at the
first engagement surface 53 and an opening 59 at the second
engagement surface 55 for transmitting a molten or semi-molten
metal charge under pressure through the passage 54. A cooling
channel 56 is located within the body 51 for circulating a fluid
therethrough to absorb heat from the metal charge located within at
least a portion of the shot block passage (i.e. the biscuit 60).
The plunger 48, disposed within the shot sleeve passage 52, forces
the metal charge through the shot sleeve passage 52.
[0028] With the shot block 44 located intermediate the die 50 and
the shot sleeve 46, the plunger must be capable of entering the
shot block passage 54 to continue to provide metal charge under
pressure to the die cavity. As such, while the shot sleeve 46 abuts
the shot block 44 and is held in place by convention means, the
diameter of the shot block passage 54 is substantially similar and
preferably identical to the diameter of the shot sleeve passage 52.
Thus, the shot sleeve 46 will not enter the shot block passage 54
and the shot sleeve passage 52 will align with the shot block
passage 54 to provide the molten charge. Further, such
configuration will permit the plunger to travel through the shot
sleeve passage 52 and into the shot block passage 54 to provide
molten charge under pressure.
[0029] It is preferred that both the shot sleeve passage 52 and the
shot block passage 54 be substantially cylindrical in configuration
and have a consistent diameter. Further, it is preferred that the
plunger has a diameter substantially identical to the shot sleeve
and shot block passage diameters for improved transmittal of molten
charge. However, it should be clear that any consistent
configuration of the shot sleeve passage, the shot block passage,
and the plunger will perform in the same manner, provided that
their cross-sectional configurations are consistent. Such
configuration could include, but are not limited to, square,
rectangular, oval, circular, triangular, etc.
[0030] The device and method of the present invention is an
improvement over the prior art by providing a shortened shot sleeve
46 so as to provide direct cooling to the biscuit via the shot
block 44 having cooling channels 56. The cooling channel 56 is
located radially outwardly from the shot block passage 54. As best
shown in FIGS. 4 through 6, the cooling channel 56 extends
longitudinally within said shot block 44 and extends at least
partially circumferentially about the shot block passage 54. As
such, the cooling fluid can be transmitted around at least a
portion of the shot block passage 54 to dissipate heat in the
biscuit 60 to promote increased cooling thereto. Therefore, heat
transfer is optimized from the solidifying metal charge to gain a
significant reduction in cycle time where the biscuit
solidification time is the determinant. This technology can also be
used in heavy runner blocks.
[0031] As indicated in FIG. 3, the shot block 44 can be
manufactured using the Direct Metal Deposition (DMD) technique
which utilizes a laser under CNC control to melt metal powder that
rapidly solidifies (thereby providing a small heat-affected zone
and a fine grain structure). Pass by pass, layer upon layer, the
object is built up, finally resulting in the finished object.
[0032] While the invention has been described with reference to the
preferred embodiment, other embodiments, modifications, and
alternations that occur to one skilled in the art upon reading and
understanding of this specification are covered to the extent that
they fall within the scope of the appended claims.
* * * * *