CAD-CAM Technology

(CIM) computer integrated manufacturing is a recent technology being tried in advance computer and it comprises a combination of software and hardware for product design, product planning, product control, product equipment and product process.

In this CIM technology CAD/CAM play an effective role. CAD/CAM system is ideally suited for designing and manufacturing mechanical components of free from complex 2-dimensional and 3-dimensional shapes.

CAD/CAM technology plays an important role in functioning of robots. In CAD/CAM system the robot work data is prepared from CAD data from the first designing process. This system is a kind of off-line teaching system. Since an actual robot is not used to input data for path creation, the coordinate system data must be corrected and simulations necessary before loading a created data.

 

 

 

Robots are inevitable for application in the field where the work is extremely difficult or impossible for human being to perform.

Some of such examples are: Work requiring speed, precision or function exceeding human ability, or that which requires entering a sterile environment, vacuum, outer space, or around a nuclear reactor, places that a man cannot enter easily or at all.

Computer Aided Design and Computer Aided Manufacture is the way things are made these days. Without this technology we wouldn’t have the range and quality of products available or, at least, they wouldn’t be available at a price most of us can afford.

Hand-building and manual techniques still very much have their place and Design Education needs to treasure and foster these skills so that future generations will have the ‘hands-on’ skills to understand the man-made world and provide the next generation of engineers, designers and technicians.

All of these professionals will be using CAD/CAM techniques or CAD/CAM products in their work, alongside practical hands-on skill. Design and Technology education has to reflect modern practice so it is crucial that students have the opportunity to use real CAD/CAM tools in their designing and Making.

USES

Computer-aided design is one of the many tools used by engineers and designers and is used in many ways depending on the profession of the user and the type of software in question.

CAD is one part of the whole Digital Product Development (DPD) act ivity within the Product Lifecycle Management (PLM) processes, and as such is used together with other tools, which are either integrated modules or stand-alone products, such as:

• Computer-aided engineering (CAE) and Finite element analysis (FEA)
• Computer-aided manufacturing (CAM) including instructions to Computer Numerical
• Control (CNC) machines
• Photo realistic rendering
• Document management and revision control using Product Data Management (PDM).

CAD is also used for the accurate creation of photo simulations that are often required in the preparation of Environmental Impact Reports, in which computer-aided designs of intended buildings are superimposed into photographs of existing environments to represent what that locale will be like were the proposed facilities allowed to be built. Potential blockage of view corridors and shadow studies are also frequently analyzed through the use of CAD.

CAD has been proven to be useful to engineers as well. Using four properties which are history, features, parameterization, and high level constraints. The construction history can be used to look back into the model's personal features and work on the single area rather than the whole model. Parameters and constraints can be used to determine the size, shape, and other properties of the different modeling elements.

The features in the CAD system can be used for the variety of tools for measurement such as tensile strength, yield strength, electrical or electro-magnetic properties. Also its stress, strain, timing or how the element gets affected in certain temperatures, etc.

Solar Based Refrigerator

As the trend changes the consumption of electricity also increases, to reduce this we can use renewable sources such as solar energy which is world’s most rich, stable and clean source of energy having large potential and also we see that in present refrigerator system which produce cooling effect by refrigerants like CFC’s, HCFC’s, Freon, ammonia which gives a maximum efficiency but the main disadvantage is that it causes the global warming ozone depletion. Now this problem can be overcome by Peltier effect and thereby protecting the environment. In this paper to introduce the portable refrigerator using peltier module with solar energy as supply which overcomes the disadvantages of existing refrigerator with increase in population and environment degradation there is an alarming rate for thermoelectric couple system have come to rescue as these are environmental friendly, affordable and compact in size.

 

Solar Panel
Solar panels are used to convert solar radiation into electrical energy. Photovoltaic (PV) modules are used.

Charge Controller
A charge controller or charge regulator is basically a voltage and/or current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panel going to the battery.

Battery
Solar powered refrigeration equipment, or so called off grid photo voltaic systems, run on direct-current electricity provided by solar energy. Batteries are used to store energy. In off grid PV systems batteries are essential to providing power during periods of low or no sunlight.

Advantages

High reliability.
Precise temperature control.
It occupies less space.
Eco friendly.
Noise less operation.
No Freon’s or other liquid or gaseous refrigerants required.
Low cost and high effectiveness.
Design is very simple.

Disadvantages

COP is less as compared to conventional refrigeration system.
In rainy season it cannot be possible to charge battery from solar.
It also depends on climatic conditions.

Applications

To keep medicines in rural area
Hospitals.
Small scale industries

Conclusion

Solar power nowadays is playing a major role in meeting the energy requirements of our country.It is being developed at a very fast rate and its applications in many areas are being explored. The fridge is intended at exploring the same and provides an efficient and economical solution to the areas where there is no electricity and cooling is required. This project main objective was to develop a mini compressor less solar fridge .By this we decided to conclude our solar based refrigerator project.

 

Gear Trains: Types & Gear Ratio

A gear train is a mechanical system formed by mounting gearson a frame so that the teeth of the gears engage. Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next.

Types of gear train are given below:

• Simple gear train
• Compound gear train
• Reverted gear train
• Epicyclic gear train

Simple Gear Train:
 

If there is only one gear mounted on each shaft, the gear train is known as simple gear train. that is, each shaft has only one gear.

Usually when two gears mate, they rotate opposite to each other. When we use three gears each mounted on separate shaft, the direction of rotation of the last gear will be same as that of the direction of rotation of first gear. Suppose the number of gears are increased to four the direction of rotation of first and last gear will be opposite to each other. A typical simple gear train is shown in the figure 1.
 

So from above we can conclude that in a simple gear train, if the no of gears is odd then the direction of rotation of first and last gear will be the same, it it is even, direction of rotation will be opposite. 

The speed ratio is given by, (N1/N2) = -(T2/T1), where, N1 is the speed of the driver, N2 is the speed of driven gear, T1 is the no of teeth on driver gear and T2 is the no of teeth on driven gear.

Compound gear train:

If there is more than one gear on a shaft, the gear train is said to be compound gear train. Here speed of rotation of the gears mounted on a shaft will the same and also the direction. By using this arrangement, the power will be transmitted to the shaft which is placed not in the row. The system is compact here. Also we can reduce the size of the gears using this arrangement. This is illustrated in the Figure 2.

 

Reverted gear train:

 

If the axes of driver shaft and driven shaft is co-axial, then the gear train is termed as reverted gear train. This is kind of compound gear train. This is illustrated in the figure 3. So reverted gear train may be called as a compund gear train but all compound gear train can not be a reverted gear train. This reverted technology is very much useful when the power is to be transmitted within the less space. 

 

Epicyclic gear train:

 

This is important gear train compared the said above. In this case, One of the gear is rotating over and around another gear. Epi means over, Cyclic means around. There is an arm connecting such two gears. This gear train finds great application in various field. This is illustrated in the figure 4.

Modes of Heat Transfer – Conduction, Convection & Radiation

Heat is a form of energy which transfers between bodies which are kept under thermal interactions. When a temperature difference occurs between two bodies or a body with its surroundings, heat transfer occurs. In this article, we are going to deal with the different modes of heat transfer. Heat transfer occurs basically in three modes:

1. Conduction
2. Convection and
3. Radiation

CONDUCTION:

 
Conduction is the mode of heat transfer occurs from one part of a substance to another part of within the substance itself or with another substance which is placed in physical contact. In conduction, there is no noticeable movement of molecules. You might be think that then how this heat transfer occurs? The heat transfer occurs here by the two mechanisms happen.

By the transfer of free electrons. (Good conductors like metals have a plenty of free electrons to make conductive heat transfer. The atoms and molecules having energy will pass those energy they have with their adjacent atoms or molecules by means of lattice vibrations.

Now we can think how this conduction occurs in gases and liquids. In the cases of gases, the molecules having energy in the form of kinetic energy and during their random movements, they exchange their momentum and energy by colliding with others. By doing so, the first molecule loses the energy while the second one gains it. This is how energy is transferred in the case of gases.

In the case of liquids also, the working is similar to that of gases. Here, the only difference is that, the molecules in liquids are more closely packed and hence inter molecular forces came into action in the case of liquids.

Fourier Law of Conduction:

Q = -kAdT/dx
Where:  Q is the heat flow rate by conduction
              K is the thermal conductivity of the material
              A is the cross sectional area normal to direction of heat flow and
              dT/dx is the temperature gradient of the section.

CONVECTION:

Conductive heat transfer occurs within a fluid itself and it is carried out by transfer of one fraction of the fluid to the remaining portion. Hence unlike conduction, transfer of molecules occurs during convection. Since movement of particles constitutes convection, it is the macro form of heat transfer. Also convection is only [possible in fluids where the particles can moved easily and the rate of convective heat transfer depends on the rate of flow to a great extend. Convection can be of two types:

Natural convection: In this type of convection, the movement of particles which constitutes convection occurs by the variation in densities of the fluids. As we already know, as temperature increases, the density decreases and this variation in density will force the fluid to move through the volume. This cause convection to occur.

Forced Convection: The difference between natural convection and forced convection is that in forced convection, a work is done to make movement in the fluid. This is done using a pump or blower.

Newton’s Low Of Cooling:

Q = hA(Ts-T∞)
Where:  Ts is the surface temperature
              T∞ is the fluid temperature
              h is the heat transfer coefficient

RADIATION:

Radiation is the third mode of heat transfer. This mode of heat transfer didn’t require any medium to occur. Every matter having a temperature above absolute zero will emit energy in the form of electromagnetic waves and called radiation. It is the same way the energy of the Sun reach us. The key features about radiation are it do not require any medium and also laws of reflection is applicable for radiation.

Stefan- Boltzman Law:

Q = A∑Ts⁴
Where:  Ts is the absolute temperature of surface
              ∑ is the proportionality constant.

Generating Electricity from a Bicycle Dynamo

The proposed mini-electricity generator project is very simple to build and can be used by students as a school project, or just for hobbyists. The set up can be used to charge a battery with electricity produced from wind power.A dynamo is a type of alternator commonly associated with bicycles for generating electricity that is used for lighting a small head lamp. The unit eliminates the need of a battery and provides an easy alternative for illuminating a lamp whenever the bicycle is in motion.

A dynamo is a type of alternator commonly associated with bicycles for generating electricity that is used for lighting a small head lamp. The unit eliminates the need of a battery and provides an easy alternative for illuminating a lamp whenever the bicycle is in motion.

A dynamo is a pretty interesting little generator which starts generating pure electricity the moment its wheel is rotated. Basically, it works on the fundamental principles of electromagnetism where current is induced in coils of copper wire under the influence of a rotating magnetic flux, generated by alternate shifting of the magnets North and south poles.

Before we move on to the actual project, interested enthusiasts may try building a homemade dynamo with the help of the explanation provided in the following section.

How to Make a Homemade Dynamo

You will need the following materials:

• A flat iron bar = six inches long, half mm in thickness,
• Super enamelled copper wire = 28 to 30 SWG, 25 meters approximately,
• Small magnet bar = square in shape, 1.5 square inch, half mm in thickness.
• Suitable spindle, clamp, wheel mechanism set-up as discussed in the text and in the diagram.
• Torch Bulb = 3 Volts

Procedure:

Bend the iron bar in “U” shape with dimensions as shown in the diagram.
Cover the horizontal portion of the “U” with a reasonably thick paper former or insulate it with some kind of PVC tape.
 

Wind the copper wire neatly and gently over the above-dressed section of the “U” channel, through uniform overlapping steps, until you have at least 6 inches of wire ends left for external connections.
 

Take the magnet and fix it (by glueing or some other suitable method) over a central metal rod and arrange the mechanism just as directed in the diagram.
 

Connect the coil ends to a small 3-volt torch bulb.
Now it’s just a matter of rotating the central rod/magnet assembly as fast as the mechanism permits.
 

If the winding and the mechanism specifications are perfectly optimised, it will instantly produce a nice glow over the filament of the bulb.
 

Your homemade DIY dynamo is ready.
 

However, the above make cannot be even close to a readymade dynamo as far as efficiency is concerned, so for our next main project, we would want to procure a good quality readymade bicycle dynamo.