Wednesday, 16 March 2011

NSEW: Mechanical Design Engineering

As part of the National Science and Engineering Week 2011 the Librarians’ Blog for Science and Engineering is celebrating the theme of ‘communication’ by welcoming our second guest blogger, Eric Rigby of EASAT Antennas Ltd. The idea of this two-part mini series is to share experiences of work within the engineering industry.

My name is Eric Rigby and I am a Project Manager and Mechanical Design Engineer. I have been in mechanical design for more years than I care to remember but it is a field I enjoy. I have designed parts for cars, trains and aerospace in a fast moving environment, but currently designing and managing the installation of radar systems worldwide.

The age of high speed travel is known to everyone, which means that the world is getting smaller. High speed travel requires the mechanical machines to aide in movement of small and large numbers of people, these machines include pedal cycles at the slow end of transport for individuals, to cars for small numbers of people at a moderate speed, to trains, boats and planes for higher speeds to convey larger numbers of people over greater distances. All machines have to be designed specifically to carry out their function.

With the increase in speed and greater numbers travelling in individual modes of transport, safety becomes a major issue. One of the most advanced tools for monitoring speeds and distances is radar. By measuring the distance, position and height of an object through electromagnetic waves we are able to calculate the speed it is travelling at.

Radar operates by transmitting bursts of radio energy. These bursts hit any object within the vicinity which reflects a small part back towards the radar, which is then received. Providing the returning signal is strong enough (or more strictly, the return is sufficiently strong with respect to the general radio noise level in the system) the return is "seen" by the radar. By timing the difference between when any one pulse burst is transmitted and received, the range to the reflecting object is determined.

Detecting air traffic over long distances the RF (radio frequency) signals have to be radiated through 360 degrees around the RF source, the antenna, as the target object or planes can be anywhere and at any height. The RF signal or beam is transmitted through an aerial or antenna, the antenna therefore has to be rotating. The rotation device for the antenna is designed using computer aided design packages such as AutoCAD, Solidedge, Solidworks, or one of many other packages currently on the market. Solidworks is one package that I, as a design engineer, use to develop models of the machines used to rotate the antenna and to design the antenna itself. A typical antenna and drive unit is shown here in the picture below.


I designed each part of the assembly as a 3D model as well as all parts assembled together to produce the finished model of the Antenna and Drive Unit. The model design package I use also ensures all the individual parts go together without clashing. Once the model is complete, each part is converted into a 2D engineering drawing and given to the fabricator, mould maker, machinist and fitters to produce the real parts ready for assembly.

The model above shows the drive unit / gearbox. The 2 electric motors to power the rotation of the antenna, on top of the gearbox is the radar feed assembly that directs the RF signal on to the parabolic dish, which reflects the RF signal out into the sky. When the transmitted RF or radar signal strikes a target or aeroplane the reflected RF signal strikes the parabolic dish and collect through the radar feed assembly and is displayed on a monitor in the radar room of the Air Traffic Controllers. The Air Traffic Controllers use the display to ensure aeroplanes have safe flying distances apart and are not on collision courses with each other and to ensure they are flying the correct course to the destination airport.

The company I work for is a small firm known as EASAT Antennas Ltd., employing 15 people in Mechanical Design, RF Engineering and Sales. For anyone interested in seeing the wider range of products and services I help to provide take a look at the EASAT website. The company is owned by a much larger group - Goodwin PLC.

Part one featured Stephen Best of Spoonfed Media.

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