2.1.3. Drawing of a kinematic diagram.
The results, received during drawing a functional diagram, are considered to be initial data for drawing a kinematic diagram. Graphic diagram must be preceded by choice of:
-source of movement (autonomous engine, power take-off shaft,
running wheel, etc.);
-types of mechanisms according to possibility of rational movement
transmission, mechanisms loading, required kinematic accuracy, distances
between centres, values of actuators travel, of assumed gear ratios, providing
observance of limitations, specified by a request for proposal (RFP).
This choice is accompanied by power and strength analysis for serviceability study with determination of mechanism elements main parameters and gear ratios.
Kinamatic diagram must represent the whole set of kinematic eie-
«nts and their connectives, designed for performing, regulating, control and
testing of preset actuator's movements it must reflect kinematic relations
(mechanical and non-mechanical) provided inside the actuators, between separate pairs, chains and groups, and also relation with movement source.
In order to build a kinematic diagram, the following groups of elements are recommended to be used: bars, bearings (rolling bearings and plain bearings), muffs, clutches (hydraulic and friction), brakes, cam mechanisms, sliders cranks (reciprocating movement), crankshafts, connecting rods, Maltese mechanisms (discrete motion), flywheels, hydro-transmissions, gear transmissions, belt and chain transmissions, rack-and-gear drivers, screw gearing, springs.
The rules for building kinematic diagrams are conditioned by All Union State Standard-2.703-84.
As a rule kinematics diagram is drawn in the form of development. It is assumed to refine it into machine contours and also to draw it in axonometric projection. All diagram elements are represented by conditioned graphic symbols in accordance with АН-Union State Standard. Mechanisms, assembled separately, and regulated independently, are represented at the diagram in the form of removed element. Relative position of elements must correspond to initial, middle and working position of actuators. Each kinematic group name, taking into account its functional specification, is indicated on a diagram. The main characteristics and parameters of kinematic elements are indicated in the specification, drawn from corresponding group. Maximum rational speed of shafts of kinematic chains, reference and calculated data, representing time sequence of processes are assumed to be indicated. Every kinematic element, represented on a diagram is assigned. Every kinematic element represented on a diagram is assigned an ordinal number, beginning with motion source. Shafts are numbered by Roman numerals, and the rest-by Arabic ones. Elements of bought or borrowed mechanism are not numbered, and number is assigned to a whole mechanism. Mixed kinematic, elements of adjustment groups are marked at the diagram by small letters of Latin alphabet and the characteristics of the whole set are indicated at the table;
Formalization method of building kinematic diagrams has not been elaborated yet, though there are no principal difficulties on this way.
Electrical engine was chosen as a power source for the investigated shredder ИСК-3.Belt-transmission, simultaneously performing preventive functions during machine blocking or break-down, is used for torque transmitting. These elements are shown at fig.2.2.
Give Russian equivalents for the following words and memorize them:
Proceeded, autonomous engine, power take-off shaft, running wheel, rational movement transmission, loading, accuracy, actuators travel, assumed gear ratios, serviceability, determination, actuator's movements, reflect, preset, movement source, bars, rolling bearings, plain, muffs, clutches, hydraulic, friction, brakes, cam mechanisms, sliders, cranks, reciprocating movement, crankshafts, Maltese, flywheels, hydro, gear, chain, rack-and-gear drivers, screw gearings, springs, to refine, in accordance with, removed element, initial middle, working position, time sequence, shafts, Roman numerals, Arabic ones, borrowed mechanisms, torque.
Find English equivalents for the following:
Данные, отображение, загруженность, исполнительный (механизм), силовой, прочностной, стержень, подкопщик, качение, скольжение, муфта, сцепление, тормоз, кулачковый, ползун, кривошип, кулисы, гидротрансмиссия, пружина, развертка, аксонометрический, выносной, вал римский, строчный, измельчитель, поломка, регулирование, управление, стержни, подшипник(качения), фрикционный гидравлический, тормоз, крутящий, забивание, поломка.
Questions to the text:
l.What are initial data for drawing a kinematic diagram?
2.Where must the whole set of kinematic elements and their connectives be represented?
3.What groups of elements are used for building a kinematic diagram?
4.What must proceed to a graphic diagram ?
S.Are there any rules for building kinematic diagrams?
6.In what projection is a kinematic diagram drawn?
7.What do conditioned graphic symbols represent?
8.1n what form are mechanisms assembled separately and regulated independently represented?
9.What does the relative position correspond to?
lO.Where is a kinematic group name indicated?
11.When is every kinematic-element given an ordinal number?
12.What elements are not numbered?
13.How are mixed kinematic elements marked?
M.Have formalization methods of kinematic diagrams already been elaborated?
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