Pneumatic Drive Design and Design Project

Contents

Introduction

1 Static engine calculation

2 Calculation of friction in seals

3 Calculation of pneumatic drive dynamics

4 Calculation and selection of damper design parameters

5 Synthesis of control system and description of schematic diagram of drive operation

6 Description of operation of pneumatic rotary module

Conclusion

Bibliographic list

Applications

Introduction

Pneumatic control systems (PSS), along with electrical and hydraulic systems, are one of the most efficient means of automation and mechanization of production processes. Abroad, about 30% of all automated production processes are equipped with PSCs.

The equipment of PSU machines and equipment is: packaging machines up to 90%, welding and casting machines up to 70%, automatic manipulators up to 50%, blacksmith and press machines more than 30%, laundry equipment up to 40%, textile and shoe, woodworking and food equipment 20%.

The advantages of PSU are especially manifested in the mechanization and automation of the following most mass operations: clamping of parts, their fixation, quantization, assembly, control of linear dimensions, transportation, packaging and others, which allows eliminating or minimizing human participation in heavy and monotonic operations, while labor productivity on operations increases by 1.54 times.

The wide introduction of PSCs in mechanical engineering is promoted from positive qualities: relative simplicity of design and operational maintenance, low cost and quick cost recovery; reliability of operation in a wide range of temperatures, at high humidity and dust content of the environment; fire and explosion safety; the big service life reaching 1000020000 h (1050 million cycles); high speed of movement of outlet link of pneumatic actuators; ease of production and relatively easy transmission of energy (compressed air), possibility to supply them with a large number of consumers from one source; no need for protection devices in case of overload.

The purpose of this course project is to master the methods of designing the pneumatic or hydraulic drive of process machines and mechanisms used in various branches of industrial production; ability to calculate static, dynamic, flow characteristics of the drive; acquisition of skills in selection of components of distribution, control equipment and compilation of pneumatic and hydraulic drive circuits.

Description of operation of pneumatic rotary module

The sheet SHED 000.000.001 shows a pneumatic rotary module.

The module consists of a quadrant with a rotation angle of 2 radians and two dampers connected to the quadrant by clamps. Damping force is equal to 2000 N.

Compressed air at a pressure of 6 atm is supplied to the cavity of the pneumatic cylinder liner through polyvinyl chloride tubes connected to the connector (Camozzi mod. 10513/8). Air presses on the piston, thus transmitting energy to the rod-rack. Rod-rack engages with gear wheel to convert linear motion into rotary motion.

A lever is fixed on the output shaft, having a ring at the end, which comes into contact with the rods of hydraulic dampers. The damping force can be adjusted by means of an adjustment screw having a handle fitted to the screw with interference.

Conclusion

During the execution of the KP, the main parameters and the principle of operation of the rotary engine were determined. By selecting the gear parameters and the stroke length of the piston, the desired rotation angle can be obtained. It usually does not exceed 360o, but in special cases it can correspond to several revolutions of the shaft.

Replacement of two-position pneumatic cylinder with multi-position one allows to obtain several fixed positions of output shaft within rotation angle.

The main advantages of pneumatic actuators are as follows:

possibility of power supply from a centralized network at relative ease of transportation of compressed air energy over considerable distances;

high operating speeds of actuators (pneumatic motors, etc.);

fire - and air safety, provided without the use of protective equipment;

possibility of operation in a wide range of operating temperatures, in conditions of dust content, vibration, radiation;

simplicity of design and high reliability of pneumatic devices;

Ease of care and maintenance

relatively low cost and fast payback.

Disadvantages of pneumatic actuators include:

1) relatively high cost of compressed air energy, which affects the continuous consumption of compressed air and its high consumption;

2) it is impossible without the use of special devices or structures to provide the specified law of movement of the output link of the pneumatic motor;

3) instability of pneumatic engine output link speed especially at variable loads;

4) poor lubrication conditions of friction surfaces of movable elements of pneumatic devices;

5) low efficiency of pneumatic actuators;

6) the need to protect the drive elements from corrosion.