2. 5. Arrangement of a construction.
2. 5. 1. Rules of Arrangement.
Arrangement of a construction is carried out after choice of a diagram and definition of the main parameters of a machine and its constituent parts were made. It contains two stages, out-line and operating. In out-line arrangement the basic diagram and general design of a unit (sometimes, some variants of it) are elaborated. On the basis of out-line arrangement analysis, specifying operating arrangement is carried out.
There is a set of arrangement rules. Main of them are the following:
-arrangement should be started with solving main problems of
correlation of kinematics and power diagrams, correct sizes and shapes of
details, determination of their optima! mutual position, determination of kind
and shape of basic construction;
-in arrangement it is necessary to go from general to particular and
not vice versa. At a given stage clarifying of details of a construction is not
only useless, but ft is harmful, as it distracts a designer from the main prob
lems of arrangement and puts him out from a logical way of design elabora
tion;
-it is necessary to work out some variants of arrangement simulta
neously; to perform their analysis and to choose the most rational one; it is
erroneously to set direction of designing just at once, either choosing the first
design type, which crossed a designer's mind, or taking a pattern design as a
model; full variant's elaboration is not obligatory; usually pencil sketches are
enough to get an idea of variant's perceptiveness and to solve the question of
expediency of further its elaboration. It is prohibited to draw a construction in
all details, imparting it a view, which only assembly drawing in technical or
operating design possesses; to design in such a way means to doom a design
to irrationality almost certainly, as thus we receive mechanical threading of
constructing elements and units, deliberately arranged inexpediently;
-during arrangement process, the calculations, even if they are ap
proximate and rough are required to be done; the main construction details
are required to be calculated for strength and rigidity; it is impossible to trust
an eye in choosing sizes and shapes;
-It is necessary to constantly mind ..ie problems of production and
to give details technologically expedient shapes from the very beginning; an
experienced designer, arr iging a detail, makes it adaptable to manufacture
immediately; and the beginner must consult technologists constantly;
-arrangement must be held on the basis of normal dimensions (di
ameters of mounting s .faces, dimensions of keyed and splinted 'joints,
thread diameters, etc. ); it is especially important in arrangement of units with some concentric mounting surfaces, and also stepped details, shape of which largely depends upon gradation of diameters;
-it is necessary to try to obtain maximum unification of normalized
elements; elements inevitable in construction of main details and units are
recommended to be used in the rest parts of the construction;
-in arrangement all conditions proving serviceability of a unit, must
be taken into account; systems of lubrication, cooling, fastening of a unit and
attaching adjacent units to it (drive shafts, service lines, wiring) are to be
elaborated; the conditions of convenient service, inspection and regulation of
mechanisms are to be provided; materials for main details must be chosen;
ways of increase of durability, wear-resistance of rubbing joints, methods of
rust-protection must be thought over; forcing possibilities of a unit must be
investigated and their limits must be determined;
-drawing in reduced scale, especially with reductions greater than
1:2, hampers arrangement process, distorts proportions and deprives drawing
of its visuality; if sizes of an object don't allow to use scale 1:1, then separate
assembles and units of an objects should be arranged in naturalized in any
cases;
-arrangement of the simplest objects may be elaborated in one
projection, in which a construction is clarified most fully; shapes of a con
struction in transversal direction are supplied by spatial imagination; in ar
rangement of more complicated objects this method may cause considerable
errors; in these cases elaboration in all required projections and cross-
sections is obligatory;
-technique of performing arrangement drawings is a process of
continuous search, tests, estimates, elaboration of variants, their comparison
and rejection of unfit ones; it is advisable to draw with weak pencil pressure,
as in arrangement alterations follow each other and a designer works more
with eraser, than with a pencil; it isn't necessary to section-line cross-
sections, or to section-line them by hand; time shouldn't be wasted for careful
drawing of all "details". Typical details and units (fasteners, seals, rolling
bearings) are expedient to be drawn in a simplified manner; inking, hatching,
explaining of conventional signs and retouching of small details are postponed
for the final stages of arrangement, when the arrangement drawing is being
prepared for discussion.
Translate the following words into Russian with a dictionary :
Arrangement, choice, definition, constituent parts, contains, stages, outline, operating, basic diagram, general design, variants, elaborated, specifying, a set of arrangement rules, solving main problems, correlation of kinematics, correct size, shapes of details, determination, shape of basic construction, general to particular, not vice versa, clarifying, useless, harmful, distracts, problems, puts, logical way, to work out, arrangement, simultaneously, to perform, choose, rational, crossed, pattern, elaboration, obligatory, pencil sketches, enough, perceptiveness, expediency, prohibited, imparting, means, doom, threading, deliberately, inexpediently, approximate, rough, required, calculated for strength and rigidity, to mind, shapes, adaptable to manufacture immediately, consult, constantly, arrangement, be held, normal dimensions, mounting surfaces, dimensions, splinted joints, thread diameters, concentric, stepped details, depends upon, gradation, normalized elements, inevitable, the rest parts, serviceability, take into account, lubrication, cooling, fastening of a unit, attaching adjacent units, convenient service, durability, wear-resistance, rubbing joints, rust-protection, thought over, forcing possibilities, reduced scale, hampers arrangement process, distorts, deprives, visually, transversal direction, supplied, spatial imagination, complicated objects, cause, errors, elaboration, projections, obligatory, continuous, estimates, rejection, weak pencil pressure, alterations, eraser, a section-line, fasteners, seals, rolling bearings, inking, hatching, retouching, postpone.
Give English equivalents for the following :
Компоновка, определение, компоновка конструкции, эскизный, рабочий, основная схема, общая конструкция, уточняющая, размеры, формы, кинематическая и силовая схемы, целесообразное расположение, идти от общего к частному, бесполезно, вредно, отвлекает внимание, наиболее рациональный, сбивает логический ход, шаблонная конструкция, необязательно, карандашный набросок от руки, вырисовывать конструкцию, подробности, сборочный чертеж, рациональность, нанизывание конструктивных элементов, производить расчеты, ориентировочные и приближенные, прочность, жесткость, доверяться глазу, постоянно иметь в виду, технологически целесообразные формы, начинающий, обращаться к консультации технологов, посадочные поверхности, шпоночный, шлицевой, Соединение, узлы, градация диаметров, работоспособность агрегата, системы смазки, охлаждение, крепления агрегата, присоединение, смежные детали, приводной валх коммуникация, электропроводка, обслуживание, регулирование механизмов, охлаждение, осмотр, долговечность, износостойкость трущихся соединений, защита от коррозии, форсировки агрегата, уменьшенный масштаб, искажая пропорции, лишая чертеж наглядности, натуральная величина, разрабатывать в одной проекции, вызвать ошибки, сечение, поиск, проба, прикидка, сопоставление, нажим карандаша, штриховать, от руки, подробности, крепежные детали, уплотнение, пружины, подшипники качения, изображать упрощенно, обводка чертежа, штриховка, раскрытие условных изображений, подрисовывание, обсуждение.
Questions to the text;
1.What do you understand under the arrangements of a construc
tion? Speak about its stages?
2.What should the arrangement be started with?
3.What factor can put a designer out from a logical way of design
elaboration?
4.How can the most rational arrangement be achieved?
5.What can a construction in all details lead to?
6.Do designers do any calculations during the arrangement process?
Why?
7.What must both an experienced designer and a beginner mind
constantly?
8.Why must the arrangement be held on the basis of normal dimen
sions? Give examples!
9.When must a designer think about serviceability of a unit and its
limits?
10.Why must we draw in scale 1:1? What do we have, If we draw
with reductions greater than 1:2?
11.What method may cause considerable errors?
12.Why does a designer work more with eraser than with a pencil?
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