2.7.3.Designing of Details, Produced
by Plastic Metal Working.
Details, produced by this method are close to casting according to their cost. Final configuration of detail is obtained after yield point of material
is exceeded, and this fact must be taken into account. That's why a proper choice of casting material is of vital importance.
There are many ways of producing details by pressure metal working. The most widely spread of them are: forging, hot and cold stamping and bending. Such kinds of pressure metal working as deep drawing, extrusion, rotational extrusion, spinning, explosive forming are widely spread too. Details, produced by different ways, possess some common properties, which should be taken into account during designing:
- in the result of drawing and flattening the structure of material is caked, which reduces the size of grains, strength and ductility being increased simultaneously. Properly designed detail must not experience internal stresses without load;
-in the result of drawing, with regard for initial position of casting,
metal fibres must run parallel to out-line of detail. Due to it long strength un
der load across fibres becomes smaller for 30 - 35 % than in the direction
perpendicular to grains;
-during bending, internal fibres are upset, and external ones are
stretched;
-choosing material and determining type of its production , it is
necessary to take into account, how this detail is produced: in one operation
(for example, by cold stamping) or by means of producing a series from in
termediate forms (hot stamping).
During designing details, produced by plastic metal working, the demands, determined by peculiarities of separate operations of a given technological process, are to be taken into account. First of all, these are the properties of material itself: ductility, malleability, grain flow; then peculiarities of tool: parting planes of a die, sizes and position of machined surfaces, convenience of fitting. It is advisable to lower volume of finishing operations.
Allowance of produced details depend upon kind of plastic metal working. Choosing material and determining shape of detail and kind of plastic metal working after its production should be taken into account.
Translate the following words into Russian;
Metal working, castings, final configuration, take into account, of vital importance, forging, hot and cold stamping, bending, deep drawing, extrusion, spinning, explosive, flattening structure, caked, ductility, experience, internal stresses, load, ahoy, non-ferrous, malleable and high-alloy, cast iron, rows allowances, molten, chill casting, sand cores, indicated, denominator, value, with regard for, Hue to, a grain, internal, upset, stretched, intermediate, forms, hot stamping, peculiarities, to upset, malleability, grain flow, parting planes of a due sizes and position of machined surfaces, convenience of fitting, allowance, depend upon.
Give English equivalents for:
Отливки, предел текучести, штамповка, гибка, глубокая вытяжка, инструкция, ротационное выдавливание, ковка, обтачивание, штамповка взрывом, расплющивание зерна, прочность, вязкость, заготовки свинца, параллельно, осаживать, растягивать, промежуточная форма, ковкость, текучесть, разъем, крепление, изготовление.
Answer the following questions :
1.What ways of producing details by pressure processing do you
know?
2.Are there any common properties of details produced by different
ways?
3.Does the reduction of the size of grains depend on the increase of
ductility and strength?
4.What result will be achieved if a load is put parallel to the fibres of
the metal and then across the fibres of metal?
5.What form do fibers take during the bending?
6.What is it necessary to take into account choosing material and
determining the type of its production?
7.Why is it advisable to decrease the volume of finishing operations?
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