Kinematic scheme. Kinematic scheme of the drive. Kinematic schemes of mechanisms

Without a kinematic scheme, it is impossible to imagine any kind of equipment. We are talking about cars, tractors, machine tools, and about simpler types of mechanisms. In general, the kinematics is a special department in mechanics, which is aimed at studying the properties of the links of mechanisms. Science allows for kinematic analysis by studying the trajectories of the links, determining the points, positions and velocities of the elements. Achieving the final result is impossible without justifying the concept of "kinematic scheme," which will be discussed in this article.

What is a kinematic scheme? Basic concepts

If we briefly answer this question, then the kinematic scheme is a certain figure or document, if one can put it this way, on which all the mechanical links with the dimensions are shown. Very often the links of the circuit are called kinematic pairs. If we define the scientific language, then they are conjugated solid elements in the number of 2 pieces, which, due to the communication conditions, limit the movement of each other.

The presence of dimensions is necessary for carrying out the kinematic analysis, which studies the basis of movement of mechanisms, their trajectories and speed. The kinematics can be solved both graphically and experimentally.

In general, we speak of the kinematic scheme when we analyze the type of mechanism. They call a certain system of bodies, which transforms the movement of some for the required movement of others. The composition of any mechanical element includes links - several solid particles, rigidly connected to each other. The link, which is considered fixed, is called the rack.

An element of a kinematic pair or link is a system of surfaces and lines along which one link is in contact with the other. This point is also called a junction node.

Areas of application of kinematic schemes

The kinematic scheme is applied absolutely in all areas of industry - machine building, machine-tool construction, etc. All the rules of execution are regulated by a special document - the so-called GOST.

Rules for the execution of schemes

There are several basic laws for drawing up kinematic drawings:

• The document can be executed both on paper and on electronic media. It is recommended to compose design schemes on one sheet with the possibility of dividing it into the required formats when printing.
• In case of using complex schemes, the use of multimedia means is allowed, that is, it is possible to show the movement in dynamics in a visual way.

Kinematic drawings are divided into three types: basic, structural and functional. The rules for their compilation also differ from each other.

As for the schematic diagrams, the drawing must necessarily show all kinds of connections between the elements. The document is provided in the form of a sweep. The principle kinematic scheme, the designations of which the developer points to the fields, should be represented in the contour of the product in the axonometric projection. More detailed rules for their compilation can be found in accordance with GOST 2.303 and 2.701.

The main difference between the structural schemes and the principal ones is that the functional parts of the product and the relationship between them are depicted on the first. As a rule, they are presented in the form of graphic images or analytical records.

Functional diagrams illustrate the interrelationships between parts of elements that are represented by simple geometric figures.

Who regulates the correctness of drawing up schemes?

The rules of compilation are spelled out in interstate documents on standardization. For the entry into force of this document, most of the countries of the world voted many years ago. Periodically, changes are made to the GOST, which is understandable - scientific progress does not stand still, science develops, and with it, changes and regulatory documents are undergoing. In addition to the basic standard, the rules for the implementation of kinematic schemes are prescribed in the Unified System of Design Documentation.

Determination of the structure of mechanisms

As already mentioned above, all mechanisms consist of a certain number of kinematic pairs. They are divided into several main ones:

• By the form of the place of communication - to the lower and higher;
• By the method of closure;
• On the relative motion in the pair - on the translational, rotational, cylindrical, etc.

Kinematic schemes of mechanisms determine their structure. If we give this definition a definition, then this is the totality of all the elements of the device and the relations between them. In addition, in order to determine the structure of the mechanism, it is necessary to establish the composition of the incoming links.

On the basis of the above classifications, the main types of machine elements that determine its structure are distinguished:

• rack;
• Connecting rod;
• crank;
• The slider.

Types of mechanisms

There are a lot of different designs. Most often the mechanisms are divided into:

• Lever or rod;
• Frictional;
• Cam-shaped;
• Mechanisms with flexible links;
• Cogged, etc.

Among the basic classifications of mechanisms, there are those that subdivide them into three groups:

• Functional (according to the principle of the technological process);
• Structural (in structure);
• Structural-constructive (on constructive principles).

More details on the kinematic schemes will be told on the example of an electric drive.

What is a drive? Its purpose

Before talking about the kinematic drive scheme, you need to know what it is. The drive is a special device that drives the machine with an engine. In other words, the mechanism starts to move from the energy flow, which goes either from the engine, or from additional elements. The kinematic scheme of the reducer is indispensable in the study of the concept of "drive". This device is a worm gear or gear mechanism that transfers the rotation from the motor directly to the machine shaft. Its body consists of bearings, shafts and cogwheels.

Kinematic scheme of the drive

In any drive, all the elements connected with each other have a certain influence on each other. That is, studying the movement of only one link will not be enough, it is important to take into account their mutual influence. To do this, all forces in the design lead to a single point, as a rule, it is the motor shaft . The kinematic drive circuit is called equivalent, and the parameters are called reduced.

Schemes of this equipment consist of such basic elements as:

• The electric motor;
• Open transmission;
• Reducer;
• Drive shaft of the machine;
• Coupling.

This is a classic composition of the kinematic scheme, some elements may be missing.

Kinetic scheme of other mechanisms

Kinematics is a science that studies various designs, therefore, for each type of equipment its own scheme. Consider the drawing of the most common aggregate - the machine. Of course, there are a number of other mechanisms, and the study of their schemes can take a lot of time. Images of complex structures are considered in more detail by scientists, mechanics and fans of kinematics.

The machine is a simple example of a mechanism that is driven by certain forces. The design executive bodies are: a table, a support, a spindle and other details. The chains of the machine kinematics consist of different gears, which are arranged in a certain sequence. Kinematic transmission schemes Can have in their composition belt, gear or worm gear. In the drawing, all elements are designated by special signs, which are prescribed in GOST 3462-61. The kinematic diagram of the machine necessarily includes the steps of the lead screws, the worm entry modules, the number of engine revolutions, power, etc.

Modern equipment has not only mechanical transmissions, often use hydraulic or pneumatic devices, and, accordingly, in the passports of machine tools one can find not the kinematic schemes, but combined pneumohydraulic or electric ones.

The modern world of machines and parts is huge, there are thousands of different mechanisms and elements. However, each mechanical unit has its own kinematic scheme, whether it is a crane, a car suspension, a metal cutting machine or a drilling rig. Kinematic drawings and design descriptions help to understand the structure and composition of mechanisms, facilitate the process of studying the movement of elements and links in the chain. Thanks to such schemes and the science of kinematics, in general, scientific and technological progress does not stand still, there are more and more perfect mechanisms, machines and units that actively enter into our lives with you.