17-06-2013, 12:21 PM
DESIGN AND FABRICATION OF PNEUMATIC RAMMING MACHINE
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INTRODUCTION
The automatic rammer is used for ramming the sand uniformly around the pattern. It can be used even in small scale industries.
To operate this rammer an air compressor is needed. A Butt which is attached to the bottom of the piston rod does the operation of ramming. The pressure developed inside the cylinder reciprocates the piston and hence the butt.
This rammer is handled by an operator just by moving it over the molding sand. The butt rams the sand at places moved and the sand is uniformly rammed. This rammer reduces the ramming time and labor. Due to this the cost is reduced considerable. So this machine finds application in foundries.
INDUSTRIAL APPLICATION
The rammer can be handled by an operator without feeling uneasiness. No separate skill is required to operate this rammer. The operation is quick and hence it is a time saving one. The operation is easy and consumes less cost. Due to the above reasons it finds its extensive application in manufacturing industries.
It has an extensive application in both large scale and small scale industries because of its economy and easy handling.
NEED FOR AUTOMATION:
Automation can be achieved through computers, hydraulics, pneumatics, robotics, etc., of these sources, pneumatics form an attractive medium for low cost automation.
The main advantages of all pneumatic systems are economy and simplicity. Automation plays an important role in mass production.
PNEUMATICS
The word ‘pneuma’ comes from Greek and means wind. The word pneumatics is the study of air movement and its phenomena is derived from the word pneuma. Today pneumatics is mainly understood to means the application of air as a working medium in industry especially the driving and controlling of machines and equipment.
Pneumatics has for some considerable time between used for carrying out the simplest mechanical tasks in more recent times has
Played a more important role in the development of pneumatic technology for automation.
Pneumatic systems operate on a supply of compressed air which must be made available in sufficient quantity and at a pressure to suit the capacity of the system. When the pneumatic system is being adopted for the first time, however it wills indeed the necessary to deal with the question of compressed air supply.
The key part of any facility for supply of compressed air is by means using reciprocating compressor. A compressor is a machine that takes in air, gas at a certain pressure and delivered the air at a high pressure.
Compressor capacity is the actual quantity of air compressed and delivered and the volume expressed is that of that of the air at intake conditions namely at atmosphere pressure and normal ambient temperature.
SELECTION OF PNEUMATICS:
Mechanization is broadly defined as the replacement of manual effort by mechanical power. Pneumatic is an attractive medium for low Cost mechanization particularly for sequential (or) repetitive operations. Many factories and plants already have a compressed air system, which is capable of providing the power (or) energy requirements and control system (although equally pneumatic control systems may be economic and can be advantageously applied to other forms of power).
The main advantages of an all pneumatic system are usually Economic and simplicity the latter reducing maintenance to a low level. It can have out standing advantages in terms of safety.
PNEUMATIC POWER:
Pneumatic systems use pressurized gases to transmit and control power. Pneumatic systems typically use air as the fluid medium because air is safe, low cost and readily available.
THE ADVANTAGES OF PNEUMATICS:
1. Air used in pneumatic systems can be directly exhausted back
In to the surrounding environment and hence the need of special reservoirs and no-leak system designs are eliminated.
2. Pneumatic systems are simple and economical
3. Control of pneumatic systems is easier
THE DISADVANTAGES OF PNEUMATICS:
1. Pneumatic systems exhibit spongy characteristics due to compressibility of air.
2. Pneumatic pressures are quite low due to compressor design limitations(less that 250 psi).
PRODUCTION OF COMPRESSED AIR
Pneumatic systems operate on a supply of compressed air, which must be made available. In sufficient quantity and at a pressure to suit the capacity of the system. When pneumatic system is being adopted for the first time, however it wills indeed the necessary to deal with the question of compressed air supply.
The key part of any facility for supply of compressed air is by means using reciprocating compressor. A compressor is a machine that takes in air, gas at a certain pressure and delivered the air at a high pressure. Compressor capacity is the actual quantity of air compressed and delivered and the volume expressed is that of the air
At intake conditions namely at atmosphere pressure and normal ambient temperature.
Clean condition of the suction air is one of the factors, which decides the life of a compressor. Warm and moist suction air will result increased precipitation of condense from the compressed air.
Compressor may be classified in two general types.
1. Positive displacement compressor
2. Turbo compressor
Positive displacement compressors are most frequently employed for
Compressed air plant and have proved highly successful and supply air for pneumatic control application.
The types of positive compressor
1. Reciprocating type compressor
2. Rotary type compressor
PNEUMATIC CYLINDER
Pneumatic cylinders impart a force by converting the potential energy of compressed gas into kinetic energy. This is achieved by the compressed gas being able to expand, without external energy input, which itself occurs due to the pressure gradient established by the compressed gas being at a greater pressure than the atmospheric pressure. This air expansion forces a piston to move in the desired direction.
NEEDS FOR PNEUMATIC POWER
Pneumatic system use pressurized gases to transmit and control power as the name implies pneumatic systems typically use air as fluid medium because air is a safe, low cost and readily available fluid. It is particularly safe environments where an electrical spark could ignite leaks from the system components.
There are several reasons for considering the use of pneumatic system instead of hydraulic system liquid exhibit greater inertia than gases. Therefore in hydraulic system the weight of the oil is a potential problem. To design and development a material handling system for automation or semi automation of industries by using pneumatic control system which is used for low cost automation
SOLENOID VALVE
The directional valve is one of the important parts of a pneumatic system. Commonly known as DCV; this valve is used to control the direction of air flow in the pneumatic system. The directional valve does this by changing the position of its internal movable parts.
This valve was selected for speedy operation and to reduce the manual effort and also for the modification of the machine into automatic machine by means of using a solenoid valve.
A solenoid is an electrical device that converts electrical energy into straight line motion and force. These are also used to operate a mechanical operation which in turn operates the valve mechanism. Solenoid is one is which the plunger is pulled when the solenoid is energized.
The name of the parts of the solenoid should be learned so that they can be recognized when called upon to make repairs, to do service work or to install them.