EXECUTIVE SUMMARY
On May 8,
2001 a Provisional Patent Application (PPA) was filed by David J. Herron, a 47
year old metallurgical consultant, with over twenty five years serving
employers and clients in the foundry industry.
A US and PCT amended application is now filed. The said PPA is entitled:
A MOLD FILLING AND CASTING
MACHINE,
SYSTEM, PROCESS, AND METHODS
FOR CONTINUOUS, PRESSURIZED,
HIGH INTEGRITY,
MOLD FILLING AND LIQUID
TRANSFORMATION
The
invention achieves pressurized filling and solidification of moving molds
at selectable and different pressures.
SUMMARY OF THE BENEFITS OF THE INVENTION
Vertically
parted green sand molding machines presently approach production speeds of 500
molds per hour. To enable such
productivity, current pouring and filling methods must complete their operation
within the short cycle time. Even at 250
per hour, this rapid pouring or filling violates fluid flow principles for
lamellar, non-turbulent flow. Scrap
rates are excessive and elaborate methods to filter or fill the metal often
raise the cost of casting. Generally,
the molding machine production rate must simply be reduced. The Herron
Casting Machine solves this problem by filling slowly and continuously during
the rapid movement of molds.
Horizontal
molding machines cannot achieve the high speeds of vertical molding because
they require individual processing, usually with a mold flask and mold weights. Pour off labor must be amortized over fewer
molds. The Herron Casting Machine eliminates the pour off person and speeds
the horizontal process in green sand or even no-bake molding. A component of the machine functions as a
stationary flask and mold weight, while allowing intermittent mold movement. The Herron
Casting Machine improves the cost and quality of the green sand and no-bake
processes.
Exceptional
quality in lost foam and investment casting traditionally comes at a high
price. Pressurized solidification
dramatically limits productivity. Now,
with this invention, the Herron Casting
Machine flexibly applies to all of these processes, automating the filling
and feeding of molds. The cost of
processing lost foam or investment castings is greatly reduced. The quality of green sand castings is
improved. Consistency and flexibility of
the system is illustrated in the PPA:
·
Near net shape castings, such as brackets, are made at
higher production rates.
·
Investment shells, for such as turbine blades, may be
processed at much higher speeds.
·
Long castings, such as axles, are made in foam, in
loose sand molds of variable length.
·
Hollow-cast castings are rapidly and automatically
processed.
·
High elongation, automotive aluminum castings result
in vertical green sand molds.
·
For ductile iron and compacted graphite iron, a new
method of magnesium alloying is included, offering the highest recovery, precise
control, cleanest metal, and lowest cost of any other process.
OPERATION OF THE INVENTION
The novel
invention operates simply and with very few moving parts. The system is quiet, clean and contained. Hard sand molds, with or without binders,
float on a pressurized bath of liquid metal.
A restraint device resists rupture of the mold and presses the mold onto
the filling/feeding chamber to seal against runout or leakage. The molds are pushed through the unit,
maintaining connection as long as desired, even until solidified. Various methods may be used to enhance the
seal. Simple to complex furnace designs
allow any degree of time, temperature and pressure control.
At extreme
quality requirements, molds must be of fine media with low permeability and
thus require pressurized filling. Such
molds currently require elaborate set-up and do not achieve high production
rates. Pressurized, solidification
shrinkage feeding has now been identified as necessary for finest dendritic
grain structure, essential for high elongation, ultimate strength, aluminum castings. Permanent molds are thought to be
necessary. High cost, slow production is
a problem.
To meet
this quality level, the invention achieves pressurized filling and pressurized solidification
of moving molds, at selectable and different pressures. This quality level is possible at high speeds
with the dramatic cost improvements of consumable mold media. For example, high quality aluminum alloy
wheels may be produced at 1000 pieces per hour.
The invented method is detailed in FIGS. 36-38 of the PPA.
In
non-ferrous casting, metal pumping techniques have been strenuously
investigated. Unfortunately, entrained
metal oxides are often, if not always, aggravated by pumping. Filtering has also been of limited success
and requires the labor of manual setting of the filters.
In
contrast, the Herron Process uses
bottom filling and a novel filtering technique that is completely
automatic. Coupled with the ingenious
filling system and extended pressurized solidification, with flexibility for
all molding techniques and media, the Herron
Casting Machine is the ultimate solution for cost and quality control of
high-volume or low-volume, ferrous and non-ferrous castings.
BUSINESS OPPORTUNITIES
Licensing is currently available for
foundries to build their own custom equipment and operate the process under license. Certain patent pending methods to particular
castings are also available. Partners to
manufacture and market two primary business products are being solicited:
This
machine resists rupture of molds from internal pressures while allowing high
speed movement. It comes in various
lengths and with motorized assisted movement options. In the casting machine invented, the
restraining device allows much more utilization of the mold parting line
surface. Bearing surface between molds
for pushing is still to be considered, but, with the power assisted, belted,
mold restraint system and equipment, less parting line bearing surface is
needed. More castings can be in the
mold. Clearly, mold utilization and
yield is greatly improved by the subject invention, the Herron Casting Machine and Process.
THE VACUUM
AND PRESSURE CONTROLLED FILLING AND FEEDING VESSEL
This
machine comes is single or multiple chamber configurations. Automated controls allow precise and
consistent pressures, mold after mold, for filling and for feeding. The furnace is replenished at will, at one
location, achieving the energy and environmental benefits of complete
containment. Precise temperature
control, mold after mold, means consistent casting integrity including hardness
and other mechanical properties. Quiet,
clean, and safe mold processing with no pour-off labor, no under-pours, no
over-pours nor any spilled metal results with proper operation.
The two business
products together achieve higher mold utilization with reduced or eliminated
risering. Inclusions are eliminated by
the clean practices: the bottom filling,
the filtration, and controlled quiescent velocity and pressures of flowing
metal.
LONG
PRESSURIZED LINES WITH IN-SERIES FURNACES
There are
several advanced embodiments of the invention.
For instance:
In FIG. 17,
at arrow A, molten metal (600) is delivered to one efficient location far from
the molding line (not shown) at the end of the solidification feeding chamber
(414) and poured into the filling tube/chamber (550), of the primary feeding
furnace (502B), most distant from the molding machine (not shown). The furnace filling tube/chamber (550) is
open to the atmosphere, at least while being filled or replenished. Heavy inert gas may protect the metal (600).
In
operation, metal height (555) in the tube (550) is held steady regardless of
volume filled, by application of vacuum or pressure in the space (510) inside
the furnace (502B) above the metal (600).
This controls the degree of mold pressurization for solidification
feeding.
At arrow B,
metal flows through the primary furnace (502B), passes through the feeding
channel (404) and into the long feeding chamber (414). The chamber (414) is covered and sealed with
the molds, in a continuously or intermittently moving, booked mold string
(100). The sand and molds literally
float above the clean bath without spalling under the applied pressure.
At arrow C,
the pressurized molten metal flows the length of the filling/feeding device
(400), via the feeding chamber (414), feeding shrinkage in the molds above,
through the gating.
At arrow D,
remaining metal seeks the level (555) of the filled primary furnace (502B),
flowing out of the filling device (400), through another feeding channel (404),
and into the secondary feeding furnace (502D), closer to the molding machine
(not shown). Several furnaces (502
series) may be linked this way, in series, for ultra-long pressurized
solidification feeding.
This
furnace/vessel (502D) is also vacuum and pressure controlled, identically in
method, and in tandem, with the filled furnace (502B). It is allowed to overflow at arrow E to
replenish the filling furnace/vessel (501).
Final flow, at arrow F, passes from the filling furnace (501), through
the lower pressure filling channel, into the filling chamber (412) and through
the gating to fill the molds.
Metal flow
rate required, depends on mold machine cycle time and casting cavity and gating
volume. The feeding channels (404) and
filling channels (402) may be of a size, no larger than necessary, to
accomplish this flow rate, driven by the head pressures involved from the
height of metal (555) in the furnace filling tube (550). If a failure of the filling device (400)
sealing occurs, pressure in the space (510) above the metal in the furnace is
immediately released. This reduces head
pressure. With lower head pressure and a
smaller channel (402 or 404) opening, runout overflow is thus at a safer and
more manageable rate. Much of the metal
is actually captured in the furnaces in this way. Any loss may be safely collected in a
pit.
The system
is safely controlled, automatically and remotely, requiring only infrequent
checking by personnel, excepting regular replenishing of liquid metal at one
safe location, safely distant from the molding machine.
Drawings and discussion of the
following excerpts from the PPA are available:
PARALLEL MOLDING LINES
CASTING IN HORIZONTALLY PARTED
MOLDS
LOST FOAM, FULL MOLD AND INVESTMENT
CASTING
FIG. 22 of
the PPA (not shown) is a very important drawing showing the tremendous
flexibility of the casting machine and system invented. Loose sand molding using consumable patterns,
wax or foam or other material, is illustrated.
Many embodiments are illustrated or imagined from this drawing, FIG. 22.
Short run
jobbing work, even single pieces, is economically assembled into a mold string
with other types and lengths of molds.
Horizontal molds, stack molds, vertical molds, and even loose sand molds
may all be assembled together into one mold string.
This is
absolutely an incredible system! For
instance, an older foundry, using manual jolt squeeze molding, may place small
molds on the sheet of filter cloth and bury them in loose sand. By continuing with other sizes, shapes and
types of molds, gathered from locations across the foundry into one central
filling area, the number of transfer ladles and transfer distances are
reduced. Metal temperature is controlled
and energy is conserved with environmental benefits. The assembled mold string is pushed through
the casting machine. The molds moving at
a high production rate are held securely by the restraint device. The results are high casting integrity and
quality for each of the single molds as well as the high volume castings.
MOLD STITCHING AND LOOSE SAND MOLD
EXTRUDING
Mold
stitching (242) provides opportunities for elaborate molten metal filtering with
creative design of the gating. Riser
gates may attach to casting cavities through a stitch (242), so that the gates knock
off more easily, and evenly, to reduce grinding of solid metal (650)
castings.
ALLOY ADDITIONS, MODIFIERS AND
INOCULANTS
With mold
stitching, rare earth metals (i.e. magnesium) may be added in specially
designed pockets of the gating system, directly or indirectly above the filter
cloth, for the controlled production of spheroidal graphite irons, whether
fully ductile iron or compacted graphite iron.
The metal is filtered at least three times with mold stitching.
ENVIRONMENTAL BENEFITS
By choice
of designs, venting of reaction fumes can be controlled to any degree
required. Vapors associated with alloy
additions and other processes are thus accommodated.
Quote From CLAIMS [39 and
rising]:
whereby, filling of said
molds with said liquid may be un-interrupted by the movement of said molds, and
whereby, time of duration of
filling may be independent of time of movement of said molds, and
whereby, degree of
pressurization of said liquid may be maintained or varied, as selected
independently of movement of said molds, and
whereby, time of
pressurization of filled said molds may be independent of movement of said
molds, and
whereby, operations upon
said liquid may be performed within said molds while coupled to said vessel,
and
whereby, reactions of said liquid may proceed within said molds while coupled to said vessel while said molds are, continuously or intermittently, conveyed.
DETAILED GATING OF AUTOMOTIVE,
TRUCK, AND INDUSTRIAL CASTINGS
FIG. 25 of
the PPA (not shown) is an invented method for making ductile iron crankshafts,
camshafts, or similar castings.
FIG. 30
illustrates a method of making cylinder heads, bedplates, bearing caps, and
other similar castings with a gate or package core in vertical green sand molds.
Loose sand
molds may use the same methods FIGS. 25-38 detail, as additional embodiments of
the invention. The package core, when
completely closed, may be void in its casting cavities. Meltable metals, papers, or other consumable
materials, seal the gates and keep the loose sand out of the package core. Alternatively, the core package may be filled
with foam or other material.
Similarly,
the illusive goal of sound, high-molybdenum, cylinder heads is embodied and
easily accomplished by this invented system, method and equipment. Production of such castings is imagined and
illustrated in FIGS. 10, 12, 19-21, 23, and 30-32.
FIG. 32, in
addition, shows various methods to riser gate cylinder heads, bedplates and
similar castings, including feeding by pressurization from the chamber using “no-riser”
gating.
FIG. 33 shows similar methods applied to engine blocks and
similar housings.
New casting design possibilities are enabled
by the invention. For example, thin
walled, high molybdenum iron cylinder heads can be better filled and then
solidified under pressure to control isolated shrinkage areas.
CAST
ALUMINUM WHEELS ACCORDING TO THE HIGH INTEGRITY,
HIGH SPEED,
CONTINUOUS, PRESSURIZED, CASTING MACHINE
A primary
goal in the development of the Herron Casting Machine was to automate the
casting of aluminum wheels into high speed vertical green sand molds or lost
foam. Pressurized filling and
pressurized solidification are essential to achieving the necessary properties.
Plain
wheels may be produced with normal core sand at the required strength with the
casting machine equipment invented.
Highly popular, esthetic wheels can also be made using special purpose
facing cores. These may be fine grained
silica, with or without a core wash or coating.
Olivine, zircon or other minerals may be used. Semi-permanent cores of graphite or other
material may be used. Even reusable
metal dies may be used as the special purpose core riding inside the vertical
green sand molds.
This
special purpose core, for esthetic appearance, or for rapid, high quality,
chilled solidification, is of one piece construction, in the preferred
embodiment, forming the face for two wheels.
The common gating is either drilled, machined, or formed by mandrels,
through the special purpose core (199).
At shakeout (880) the gating (108) breaks from the wheel's (995) center
hub and the hub of the wheel (995) is drilled out, leaving no marks from the
gating (108).
The outer
rims of the wheels (995) are formed by two identical conventional cores (122)
of high quality. The bulk of the inside
of the wheels (995) is formed by the economical green sand (101 or 111). The early solid metal shell (650 in other drawings),
discussed elsewhere, protects the surface finish sufficiently from the higher
pressure over the secondary solidification feeding chamber (414).
Wheels may
also be produced in loose sand molding. The
cores may be bound together by consumable lost foam patterns.
A lower rim
gate (108) may be employed for completely gentle, bottom filling of the wheels. By multiplying this assembly (38, see FIG.
38), four wheels may be made in a mold, at four wheels per cycle of the molding
machine, for near 1000 wheels per hour.
THE NEXT
STEP
The
invention is largely engineered but has not been prototyped. Several independent efforts to do that are
under discussion. We expect to have a
working prototype available for visitation and tour within six months. A small and simple embodiment is sufficient
to prove the principles of operation.
I would
like to present a full disclosure and business plan to any interested parties,
particularly foundries and equipment manufacturers. My attorney assures me we have complete
protection of all rights. The period of
disclosure with trade secrecy is now ending, so we are now widely disseminating
the information. Many positive
endorsements are in hand.
Preferred
licensing arrangements will be available to those willing to build a prototype
open to outside visitors. Exclusive
partnerships to build and market the equipment are also available. Venture funding opportunities are
welcome.
Please
E-mail DHerron@HerronCasting.com
to schedule our complete
presentation. Thank you.
RE-Launch... www.HerronCasting.com
E-mail... DHerron@HerronCasting.com
Copyright© 2002, 2003, David J. Herron
All Rights Reserved
