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Master's
portal of DonNTU
Ryazantsev Igor
Faculty: physico-metallurgical
Speciality: Metallurgy of color metals
Scientific adviser: Nikolay Manyak
About
author
Investigation of the technological production of shaped
bronze ingots in the Donetsk-Kurakhovskaya mechanical plant
Introduction
Shaped castings - is a common name in the foundry of all processes
related to the production of castings with a developed spatial form
(inside the cavity, cast holes, closed form). This includes mold
casting method of casting in sand-clay molds in the form of chemically
hardening, casting into the land of cutting patterns for casting,
centrifugal casting, injection molding, casting on consumable patterns
and art casting. Each casting method has its own characteristics and
technological methods for manufacturing products, the number of
manufactured products.
Mold casting is widely used at all times of industrial growth, because
this is the way to production quickly and cheaply get the whole
machinery and household items. Mold casting is widely distributed in
machine building. With the help of this technology is up to 70% of the
mass majority of the machinery. Large complex shaped castings receive,
usually cast in a disposable form, with the rods. The use of shaped
castings quickly and accurately meet consumer demand for a short time
and in sufficient quantity.
Casting bronze casting refers to a color (the general name of the
production of castings by casting from a variety of metals not
containing iron-based).
Casting is a relatively cheap way to manufacture parts with complex
contoured shapes. It is through the technology of casting it is
possible to sufficiently fast and accurate production of large number
of similar products.
A review of research on the topic in the world
Currently in the world for fittings most promising technology of casting with vacuum film forming process.
Vacuum film forming process began to be used in the foundry industry in
70 years of the last century in Japan. And now Japan is a country where
the molding process has wider application than in European countries
and the USA. In Japan, by HWS, the main producer of equipment for the
V-process, it was delivered more than 150 lines for this forming
process, while in Europe - 40 lines. In the last decade, V-process is
recognized as an effective process for forming large-sized thin-walled
castings such as cast-iron baths (wall thickness 4mm); complex machines
deployed plates; steel castings for the railroad "side frame" and "beam
nadressornaya; valves and valves made of cast iron and steel for the
oil and gas industry, arrows and crossings for railway tracks, rear
axles of trucks and tractors, cast molds, and many other castings with
a minimum ratio of metal / shape, in small-scale and commercial
production.
The main advantages of vacuum-formed lines are: obtaining castings with
high precision geometry, with a quality surface, suitable for
subsequent coating, the absence hindered the shrinkage of the alloy,
binders, wear patterns (in this connection to make them apply easily
processed materials, which significantly reduces the time
pre-production), high ecological process of obtaining castings. Does
not require the system to smeseprigotovleniya and regeneration.
RFT - a process based on the use of dry silica sand or other refractory
filler (without binder) and synthetic ethylene vinyl acetate film.
The method and sequence of operations in the manufacture of shapes using RFT is:
- Model stove made in the form of a sealed box, the cavity is connected
with the atmosphere through channels (gates), width 0,3 - 0,5 mm, made
in the plate and in the model, and a valve connected to a vacuum system;
- Over the pattern plate is installed heater power density 15 - 20
kW/m2, with which the film is heated to 120 ° C, the film goes to a
plastic state, then it is applied to the plate with the models and
created by dilution sticks to the surface models and plate;
- The film coating is applied 0,25 - 0,4 mm antiburning coating with a
spray gun airless spraying and drying with hot air at a temperature of
65 - 70 OS;
- On the pattern plate is installed flask of special design with built-in filters and valves;
- In flasks filled dry refractory filler without a binder and compacted by vibrating table;
- If necessary, otformovyvaetsya gating funnel, then the excess sand is
removed from kontrlada semiform superimposed plastic film thinner and
of lower quality flask connected to a vacuum system, with the pattern
plate is disconnected from the vacuum source and connected to the
atmosphere;
- Half-form is removed from the pattern plate, and the flask should be permanently connected to a vacuum system;
- The lower half-form is made the same top half-forms;
- Put down the rods;
- The form is collected and filled with metal;
- After cooling form is fed to a knockout cast.
- Castings are transferred to the stumps and clean and the sand is prepared and sent for recycling;
Advanced technology of vacuum-film forming (RFT) has the following advantages:
1. the ability to completely eliminate the operations to prepare the
sand mixture and the complex mechanization and automation of the
process, ie, all operations of forming, assembly, casting and casting a
knockout;
2. allows to obtain castings with a guaranteed second class of accuracy;
3. Cast weight is reduced by 10 - 15%;
4. allowances for machining can be reduced by 50%;
5. technology is practically non-waste, the loss of sand during a turnover of up to 100 kg per 1 ton of suitable casting;
6. reduced by 50% or more obrubno-cleaning operations at the expense of
high quality castings and in the first place - clean surface;
7. dramatically increases the service life modeling equipment, you can use wooden models with long life;
8. significantly improve the hygienic conditions of work, mainly due to
the absence of binders, reducing emissions of gases and dust.
With this method it is possible to obtain castings of iron, steel and nonferrous alloys with high accuracy and surface finish.
| Important Note |
| When writing
this author's abstract, Master's work is not completed yet. Final
completion: January 2012. Full text and materials on the subject can be
obtained from the author and his manager after that date. |