27-04-2012, 07:52 PM
we need the pptx or slides for the purpose of technical seminars in our college...
kindly do reply...
27-04-2012, 07:52 PM
we need the pptx or slides for the purpose of technical seminars in our college... kindly do reply...
30-04-2012, 12:06 PM
to get information about the topic "SPECIAL PURPOSE MACHINES" full report ppt and related topic refer the link bellow https://seminarproject.net/Thread-specia...e-machines
11-05-2013, 01:39 PM
Special Purpose Machine
Special Purpose.docx (Size: 387.31 KB / Downloads: 45) INTRODUCTION In contrast to standard machine tools, special-purpose machine tools have their construction, tooling, work location and kinematics designed for specific operations. Some of such machines, e.g. railway-axle lathes and drilling machines with interchangeable drilling heads, have been discussed in previous chapters as special versions of standard machines. In this chapter, further special-purpose machine tools are described, but owing to the great variety of such machines, this presentation does not claim to be complete. By capturing the tiny amounts of current produced by hundreds of nanowires kept in motion, the generators produce a direct current output in the Nano-Ampere range. If we had a device like this in our shoes when we walked, we would be able to generate our own small current to power small electronics. Anything that makes the nanowires move within the generator can be used for generating power. Very little force is required to move them. Here, by using special purpose machines we introduce some of these machines and their applications in various fields. The recent developed technology of Nano generators is included and its working is also explained. NANO GENERATOR Researchers have demonstrated a prototype nanometer-scale generator that produces continuous direct-current electricity by harvesting mechanical energy from such environmental sources as ultrasonic waves, mechanical vibration or blood flow. The Nano generators take advantage of the unique coupled piezoelectric and semi conducting properties of zinc oxide nanostructures, which produce small electrical charges. NANO MOTOR Even smaller motors have been made using nanotechnology. An example is shown below. It consists of a tiny gold slab rotor, about 100 nm square, mounted on concentric carbon nanotubes.The outer tube carries the rotor, driven by electrostatic electrodes, rotating around an inner tube which acts as a supporting shaft. By applying voltage pulses of up to 5 Volts between the rotor plate and stators, the position, speed and direction of rotation of the rotor can be controlled. It measures about 500 nanometers across, 300 times smaller than the diameter of a human hair. PRINTED CIRCUIT (PCB) OR "PANCAKE" MOTOR: The printed circuit motor is an example of an ironless or coreless motor with several unique features. The pancake construction uses an axial magnetic field to achieve the short flat construction. Radial field PCB motors are also possible. CONSTRUCTION The rotor windings are printed, stamped or welded onto a thin, disc shaped glass fibre circuit board which rotates in the air gap between pairs of permanent magnets arranged around the periphery of the disk. The windings fan out in a series of radial loops around the surface of the disk. The magnets are arranged alternatively north and south so that the magnetic fields in the air gaps of adjacent magnet pairs are in opposite directions. The magnets are held in place by two iron end caps in a compact "pancake" shaped block to complete the magnetic circuit. Current is fed to the rotor windings via brushes through precious metal commutator segments printed on the disc. PRINTED CIRCUIT (PCB) OR "PANCAKE" MOTOR: The printed circuit motor is an example of an ironless or coreless motor with several unique features. The pancake construction uses an axial magnetic field to achieve the short flat construction. Radial field PCB motors are also possible. CONSTRUCTION The rotor windings are printed, stamped or welded onto a thin, disc shaped glass fibre circuit board which rotates in the air gap between pairs of permanent magnets arranged around the periphery of the disk. The windings fan out in a series of radial loops around the surface of the disk. The magnets are arranged alternatively north and south so that the magnetic fields in the air gaps of adjacent magnet pairs are in opposite directions. The magnets are held in place by two iron end caps in a compact "pancake" shaped block to complete the magnetic circuit. Current is fed to the rotor windings via brushes through precious metal commutator segments printed on the disc. OPERATING PRINCIPLE Traditional electric motors have a radial magnetic field or flux with the rotor current flowing axially along the length of the rotor. In typical printed circuit motors the construction is reversed. The magnetic field is axial (oriented along the axis of the machine) and the current flows radially from the axis to the edge of the disc and back again. A tangential force on the disk is created by the current passing through the magnetic fields in the air gaps between the pole pairs of the permanent magnets. So that the return current does not cancel out the effect of the outgoing current, the return wire is physically separated or displaced to one side from the outgoing wire by the width of the magnet. In this way it interacts with the magnetic field of the adjacent magnet which is in the opposite direction and thus reinforces the tangential force on the disk. CONCLUSION All these special machines play a key role in their respective fields. These machines reduce the time of operation of the system and at the same time provide smooth operation. The researchers of Nano generator said, “You could envision having these Nano generators in your shoes to produce electricity as you walk. This could be beneficial to soldiers in the field, who now depend on batteries to power their electrical equipment. As long as the soldiers were moving, they could generate electricity.”This statement indicates the importance of the special machines. |
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