In 1958, H.F. Shroyer invented and patented the technology for making metal
castings from expandable foam models. The original model was made from
polystyrene (EPS) sheets and was molded with a binder-containing molding sand.
Germany's Grünzweig and Harrtmann purchased the patent and developed it. The
technique of producing castings using binderless dry sand was later patented by
T.R. Smith in 1964. The use of a binderless dry sand process prior to 1980 must
be approved by the Full Mold Process, Inc., after which the patent is
ineffective.
The most common and practical method is to put the refractory coated model
into the sand box, the model is filled with dry sand and compacted, and the
liquid metal is poured instead of the foam plastic mold. This casting process is
called: lost foam casting ( EPC), gasification die casting and solid casting.
The Lost Foam Casting Committee of the American Foundry Association adopted
"foam casting" as the name of the process. Precision casting
Lost Foam Casting is an innovative casting process that can be used to
produce parts for both colored and ferrous metal power systems, including:
cylinder blocks, cylinder heads, crankshafts, gearboxes, intake manifolds,
exhaust pipes and brake hubs. The process flow of lost foam casting is as
follows:
1) Pre-expansion
Model production is the first process of the lost foam casting process.
Complex castings, such as cylinder heads, need to be made separately from
several foam models, and then glued into a whole model. Each block model
requires a set of molds for production. In addition, a set of tires may be
needed in the gluing operation to maintain the accurate positioning of each
block. The molding process of the model is divided into two steps. The first
step is to Polystyrene beads are pre-expanded to a suitable density, typically
by rapid steam heating, which is known as pre-expansion.
2) Model molding
The pre-expanded beads are first stabilized, then sent to the hopper of the
molding machine, and fed through the feeding hole. After the mold cavity is
filled with the pre-formed beads, steam is introduced to soften the beads.
Expanding, squeezing all the voids and bonding them together completes the
manufacturing process of the foam model, which is called autoclaving.
After molding, the model is cooled by a large flow of water in the
water-cooling cavity of the mold, and then the mold is opened to take out the
model. At this time, the model temperature is increased and the strength is low,
so care must be taken during demolding and storage to prevent deformation and
damage.
3) Model cluster combination
Before the model is used, it must be stored for a suitable time to make it
mature. The typical model storage period is up to 30 days. For the model formed
by the uniquely designed mold, it only needs to be stored for 2 hours. After the
model is matured, it can be divided. The block model is glued together.
The block model is glued using a hot melt adhesive on an automatic glue
machine. Glued joint seams should be tightly sealed to reduce the possibility of
casting defects
4) Model cluster dip coating
In order to produce more castings per box casting, sometimes many models are
glued into clusters, the model clusters are immersed in refractory coatings, and
then dried in air circulating ovens of about 30-60 C (86-140 F) for 2 to 3 After
the hour, after drying, put the model cluster into the sand box, and fill the
dry sand to make the vibration tight. The inner cavity of all the model clusters
and the dry sand of the periphery must be compacted and supported.
5) Pouring
After the model cluster is filled in the sand box by dry sand vibration, the
mold can be poured, and the molten metal is poured into the mold (casting
temperature is about 760C/1400F, cast iron is about 1425C/2600F), and the model
gasification is The metal is replaced by a casting. Figure 1 is a schematic view
of a flask and casting of a lost foam process.
In the lost foam casting process, the casting speed is more critical than
conventional hollow casting. If the casting process is interrupted, the sand
pattern may collapse and cause waste. Therefore, in order to reduce the
difference between each casting, it is best to use an automatic pouring
machine.
6) Falling sand cleaning
After casting, the casting solidifies and cools in the flask and then falls.
Casting sand is quite simple, and the tilting sandbox castings fall out of the
loose dry sand. The castings are then automatically separated, cleaned,
inspected and placed in a casting box for transport.
Dry sand can be reused after cooling, and other additional processes are
rarely used, and metal scrap can be remelted in production.
Posted to casting
10/10/2018
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Fly Fishing Sunglasses for Nymph Fishing Another item of heavy importance is a
good pair of polarizedsunglasses. Strike indicatorsare generally bright orange,
ungodly looking things that get puton your leader well above the fly or on the
fly line itself, atthe junction of the fly line and leader. These strike
indicatorsare what you look at when CNC
Machine nymph fishing not the fly itself.Strike Indicators for Nymph
FishingFirst, you will need some strike indicators. Its absolutely imperative
that you be able to seethe strike indicator, and polarized sunglasses are very
effectivefor this.Exactly where to put the strike indicator is a matter of
somedebate, but ultimately boils down to what you are fly fishing forand where
you are doing it.Now that weve covered what nymph fly fishing is all about,
letsnext take a look at what sort of fly fishing gear you're going toneed to do
it.
Small Weights for Nymph FishingThe second thing youll need for many rivers
will be some smallweights to add to your fly line or leader. Using these types
of weights, an anglercan put on as much or as little weight as needed to bring
the flydown to depth, while at the same time preventing the fish frominhaling
toxic lead (which can kill them). Theseitems are strike indicators, some small
weights, and a good pairof fly fishing sunglasses. While nymph fly fishing uses
pretty much the samegear you use when dry fly fishing, there is a few small
itemsthat any successfully nymph fisherman will want to have. Wary Brown Trout
in heavily fishedwaters, like the Missouri River, are not likely to be real
wildabout seeing a bright orange object just a few feet above thefly.
Sink-tip
fly lines have the tip of the flyline weighted to sink, thus allowing it to sink
the nymph flymore quickly.With practice and patience, youll eventually be able
to tellwhen unnatural movements occur in the strike indicator whichmost
likely indicates that a fish just took your nymph flyimitation.This is best done
with the newer twist on non-toxic weightsthat are now available. . Inshort,
use your judgment, erring on the side of caution (placingthe strike indicator as
far away from the fly as possible, foryour abilities). On the other hand, more
gullible trout or trout that receiveless fly fishing pressure could probably
care less about it.Should you plan on fishing in really deep or fast rivers
whereeven a weighted leader will not get the fly down to depth fastenough, then
you will also want to look at investing in asink-tip fly line. In many, if not
mostnymph fly fishing situations, a floating line is still used.However, to get
the fly down to the depth you want it to go willrequire weighting it (at least
in faster water)
Posted to Generalna
09/18/2018
Edit
When searching for an appropriate casting torch the hobbyist will need to
takeseveral things into consideration. If the hobbyist plans to use natural gas
like the kind that is providein households they may find that the pressure is
just not enough and thedesired temperatures will not be reached.All the metal
caster needs is an idea and red hot liquid metal. One of the furnaces functions
isto help the flame reach optimum temperature and in the case of
ReverberatoryFurnaces, a furnace torch is an absolute requirement.Several online
shops also sell torches for the hobby metal caster. The size of the furnace, and
what metals youplan to use are chief among the considerations. Don't worry, this
is completelynatural.Price is brass Bushings
suppliers yet another consideration. The same is true for Butane. Always
usecaution when dealing with a furnace torch. Most hobbyists begin theircasting
careers with a modest sized furnace to fit their most basic needs. Many think
that just because you need afurnace torch you are going to need a large furnace.
Many jewelers are able to use small independent casting torches but whendealing
with metal casting in furnaces you will need to use a torch that can bemounted
and used in such a fashion.To say that metal casting is addictive is an
understatement.The furnace is the pride and joy for the metal caster. .Within a
few months, the hobbyist might find that the furnace has grown andthat they are
casting at every chance that comes along. This is simply nottrue.Casting torches
can be found in some hobby shops and in hardware stores. When buyinga torch
hobbyist should shop around in order to find the best deal.Oxyacetylene torches
are a favorite with many casters especially for castingiron. Many casters will
use a torchthat uses propane gas as it provides enough pressure and heat to melt
mostmetals.MetalCasting provides the hobbyist with a great way to create
personalized parts andpieces that may otherwise be unattainable or far too
expensive.
Except as a paper weight; a very ugly paperweight. This skill is a
valuable one that promises toprovide the hobbyist with a rewarding past time.
Most will constructtheir own furnace tweaking the design here and there to
better suit theirneeds. This is perhapsone of the greatest parts of the entire
metal casting process like seeing whatwas once just sketches solidify from
liquid iron, or whatever metal is used. Casting is anancient art that is still
is use to this day by major industries to artists tothose with backyard
foundries. Torches can range in price from $40 toseveral hundreds of dollars
depending upon the size, the use, and accessories. Whilenatural gas and Butane
can be used, propane seems to yield the best results. While it may be possible
to rig a castingfurnace it is not always advisable. Many home foundries are
based on home made furnaces and if constructedcorrectly can prove to be highly
effective. A small furnace and furnace torch can produce enough heat to
meltaluminum, iron, and a number of other metals. Metal castingprovides a way
for an idea to materialize through molten metal. The crucial part of thefurnace
is the furnace torch. The torch brings the heat, incredibly high heat,and
without it that chunk of metal would just sit in the crucible and never seelife
as something new and exciting
Posted to casting
09/05/2018
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Posted to Generalna
08/21/2018
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