Exhaust press mechanism - Coursework by TMM
- Added: 08.11.2014
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1. Structural and kinematic examination of lever mechanism
2. Power calculation of lever mechanism
3. Flywheel Calculation
4. Gear Design
1 Structural and kinematic examination of lever
1.1 Structural study of the mechanism
1.2 Construction of Provisions Plans
1.3 Construction of speed plans
1.4 Construction of acceleration plans
1.5 Hodographs of speeds and accelerations of mass centers of links
1.6 Kinematic diagrams of the mechanism output link
1.6.1 Movement diagram
1.6.2 Speed diagram
1.6.3 Acceleration diagram
1.7 Control of construction accuracy
2 Power calculation of lever mechanism
2.1 Determination of forces of useful resistance
2.3 Determination of inertia force of links
2.4 Determination of reactions in kinematic pairs of mechanism
2.4.1 Operating stroke
2.4.2 Idle stroke
2.5 Power calculation of input link
2.5.1 Operating stroke
2.5.2 Idle stroke
2.6 Determination of balancing force according to the method of N. E. Zhukovsky
2.6.1 Operating stroke
2.6.2 Idle stroke
2.7 Check of construction accuracy
2.7.1 Operating stroke
2.7.2 Idle stroke
3 Flywheel calculation
3.1 Diagram of forces of useful resistances
3.3 Construction of diagrams of operations of reduced resistance forces
and driving forces
3.4 Diagram of kinetic energy of the whole machine
3.5 Construction of kinetic energy of mechanism links
3.6 Diagram of kinetic energy of flywheel
4 Gearing calculation
4.1 Gear Design
4.1.1 Determination of displacement factor
4.1.2 Determine the engagement dimensions
4.2 Construction of Engagement Pattern
4.3 Calculation of specific slides of tooth profiles
List of literature
The theory of mechanisms and machines (TMM) is one of the main engineering disciplines. It is devoted to the study of general methods for the study of mechanisms and machines and the design of their schemes .
The main issues being addressed by TMM are:
- study of structure (structure) of mechanisms;
- determination of positions of mechanisms and trajectories described by individual points;
- determination of speeds and accelerations of individual points and blades;
- analysis and design of various mechanisms (gear, cam, lever);
- determination of different forces (external, reactions, friction, inertia) acting on the links of the mechanism;
- study of the energy balance of machines (k.k.d. and so forth);
- study of the actual law of movement of machines under the influence of given forces;
- Studying methods of controlling the speed of the machine;
- studying methods of balancing inertia forces in machines and the like.
In accordance with these issues, the theory of mechanisms and machines is a science that studies the structure, kinematics and dynamics of mechanisms and machines.
Simple mechanisms (lever, gear, and the like) have been known since ancient times; Gradually, they were studied, improved and put into practice in order to facilitate human work and increase productivity.
Yes, it is known that the outstanding Renaissance figure and scientist Leonardo da Vinci (14521519) developed designs for the mechanisms of looms, printing and woodworking machines, he made an attempt to determine the coefficient of friction by experimental means. The Italian physician and mathematician D. Kardan (15011576) studied the movement of the mechanisms of watches and mills. French scientists G. Amonton (16631703) and S. Coulon (17361806) were the first to propose formulas for determining the friction forces of rest and sliding.
Outstanding mathematician and mechanic L. Eiler (17071783), Swiss by origin, for thirty years he lived and worked in Russia, professor, and then full member of the St. Petersburg Academy of Sciences, the author of 850 scientific papers, unleashed a number of problems from kinematics and solid state dynamics, studied the oscillation and persistence of solids, dealt with practical mechanics, studied, in particular, the various profiles of gear teeth and came to the conclusion that the most promising profile is involute.
The science of mechanisms and machines arose at the end of the 18th century, inextricably linked with
the development of the machine production method, which required the solution of a number of practical problems related to the action of machines.
The Russian school of the theory of mechanisms and machines originated in the middle of the XIX century. Its founder is the great mathematician and mechanic academician P. L. Chebyshev (18211894).
P. L. Chebyshev played an outstanding role in the development of modern mathematics and mechanics. His research is also important in our time, and original constructive solutions and the development of mechanisms have provided some modern solutions in this area. Its structural formula for determining the number of degrees of freedom of a flat mechanism is very popular, in particular.
Among Chebyshev's followers is Professor I. A. Vishnegradsky, who developed the classical theory of machine regulation, introduced the teaching of mechanical engineering in Russia and contributed to the training of personnel for this industry.
For the development of the theory of mechanisms and machines, the work of the Russian scientist L.V. Assur, who created a rational classification of elementary groups that create lever mechanisms (in 1913), is extremely important. The clear principles of this classification served as the basis for the largest generalizing works on the theory of mechanisms and machines already in the Soviet period.
The development of the ideas of P. L. Chebyshev, I. A. Vishnegradsky, L. V. Assur and others was successfully extended by outstanding scientists N. E. Zhukovsky, S. A. Chapligin, V. P. Goryachkin, N. I. Mertsalov and others.
The most important works of N.E. Zhukovsky are devoted mainly to the theoretical foundations of aviation, research in the field of friction and a number of problems in kinematics and machine dynamics. Theoretically and experimentally, the phenomenon of spring sliding in the belt of a belt transmission was studied and the task of distributing the load between threads in a threaded connection was untied.
The fundamental ideas of L. V. Assur are especially fully reflected in the works of I. I. Artobolevsky, N. G. Bruevich, V. V. Dobvolovsky, G. G. Baranov and others.
S. I. Artobolevsky, Z. Sh. Bloch, Kh. F. Ketov, S. N. Kozhevnikov, N. I. Kolchin, A. P. Malishev, L. P. Smirnov, V. A. Yudin and others made a great contribution to the development of the theory of mechanisms and machines.
N.P. Petrov laid the foundation for the hydrodynamic theory of oil (in 1883), developed regarding the issue of friction in the bearing.
Developed in the XVIII century by L. Eiler, the theory of involute engagement contributed to the development of gears.
The theory of mechanisms and machines in its modern form is a complex science in which the problems of kinematics and dynamics of mechanisms and machines, their analysis and synthesis are closely
intertwined with the theory of optimal design and control.
One of the main areas of development of modern technology is automation of all types of production. Robotic systems make a great contribution to solving this problem. Already at the moment, in the industry, many types of robotic systems perform loading, warehousing, and compiling simple units.
The revolutionary role in the control systems of automation of production was played by the appearance of computers. With the help of computers, it became possible to analyze multi-link, with a large number of degrees of freedom mechanisms, solving problems of optimal synthesis of both individual mechanisms and complex automatic machines, solving design problems of many criterion and many parametric machine devices, software control of most modern machines, controlling new machines with biomechanical devices such as manipulators, robots, walking machines and the like.
Newly created automatic machines must meet the requirements of high efficiency of a given technological process and have automatic control, which maximally frees a person from monitoring the operation of the machine.
Since in solving the problems of synthesis of mechanisms we are dealing with multicriterial systems, the problems of synthesis are associated with the search for optimal options. Finding optimal variants or regions in which these variants exist requires the development of the theory of optimal synthesis of mechanisms. Solving these problems, as a rule, is possible only with the help of computers, and this requires the development of appropriate algorithms and programs.
Great tasks are in the field of analysis and synthesis of transmission mechanisms. Here, first of all, it is necessary to note the need for the subsequent development of the synthesis of gears, especially spatial ones. It is also necessary to further develop the theory and methods of designing complex gear gears with planetary and differential circuits. Theories and methods for the synthesis of wave transmissions are rapidly developing. Almost all industries need reliable mechanisms with a stepless change in the transfer function. The theory of mechanisms that carry out movement with stops, such as Maltese, ratchet, levers and the like, should be developed.
Recently, machine speeds have increased significantly, which has led not only to an increase in dynamic loads on the mechanism links and working elements of the machine, but also to a significant increase in the level of vibration and noise. Therefore, recently, the problems of vibration protection of machines and reducing the noise level of machines have also been studied in the theory of mechanisms and machines.
But, as before, the most important task of the theory of mechanisms and machines will be the development of experimental methods for studying the characteristics of different machines and mechanisms. At the same time, experimental studies of automatic operation machine systems under the conditions of their production operation with automatic recording and processing of the received information on computers will acquire particular importance.
Structural and kinematic examination of lever mechanism
1.5 Hodographs of speeds and accelerations of mass centers of links
The godograph (from Greek hodos - path, movement, direction and grapho - I write) in mechanics is a curve that is the geometric place of the ends of a variable (changing over time) vector, the values of which at different points in time are deposited from the common beginning of O.
The concept of a hodographer was introduced by the English scientist W. Hamilton.
The godograph gives a visual geometric idea of how the physical quantity depicted by the variable vector changes over time and the speed of this change, which has a tangent direction to the godograph.
To construct a speed hodograph, we transfer the psi vectors parallel to ourselves with our principles to one point p, called the pole. Connect the ends of the smooth curve vectors.
To construct an acceleration hodograph, we transfer the psi vectors parallel to ourselves with our principles to one point p, called the pole. Connect the ends of the smooth curve vectors.