Design on Roasting Meat in an Open Space - Report Example

Mechanism Name Institution of Affiliation Date Design brief Roasting meat on open space is a very enjoyable activity which serves to bring a lot of people together through interaction. For this reason, it has proven to be a tradition which is hard to stop. It has become an economic activity where it is done for a living. People flow to places where such services are offered and it has increased greatly. For this reason it has become important to increase the capacity of the spit roast so that it handle several animals simultaneously. In this case the design is for a system that can take four animals simultaneously without giving trouble to one cook operating it. It is good to understand that a motor can be employed to aid the process because the amount of energy required cannot be provided by a man. It has a safety rule that heavy loads should not be lifted by men because of injuries. The system is expected to handle 200kg of load simultaneously. The system has to be simple so that repair, operation and replacements are simple and can be performed by a person with very minimal technical knowhow. The materials used to make it has very long life span and if carefully protected against water, it can last for more than four decades. Mechanical analysis The power requirement of the system is one that should handle 50kg. The assumptions here is that all power required is supplied by motor which can only provide great power. This is to mean that the whole batch has to turn simultaneously. A system of pulleys, belts and shafts are required. The total force required to turn the load; Force = number of animals * average weight Equation 1 = 4 * 50kg = 200kg (1962N) The motor has to turn at very small speed of around 2.5 rpm. This will ensure that the system gives the meat enough time to be exposed to heat for cooking. This speed can be converted into angular velocity by the formula below; ω= Equation 2 Where N is the number of revolution per minute and ω is the angular velocity. ω = = 0.261833 rad/ s This can be converted further into linear velocity as shown below; V= ω r Equation 3 Where v is the linear velocity and r is the radius of the wheel. Assuming that the radius is 20mm (2cm) Then V= 0.261833 * 0.02 = 0.005237 m/s The power required is therefore given by the formula below; Power= force * speed Equation 4 Power = 1962N *0.005237 m/s = 10.27434W 10.27434W is applied to aid in the power transmission from the pulley. The system design and components The diagram below shows how the system will work. It is simple and very effective. Figure 1: The side view of the turning subsystem Figure 2: Top view of the turning subsystem How system works The system is very simple in the design and also in the operation. The system is designed to be operated by a single cook where by the serving staffs can access any portion of meat roasting at any time. Most of the work is done by the motor. There are three belts that are hang loosely around the motor. The belts are tightened by the levers located sideways. Lever one is used when the cook wants to have the meat turning. Lever three is used when s/he wants to remove the meat from the fire. Lever two is used when the cook needs to lift the meat some distance away from the fire so that it can be taken away from fire. So that the meat can be rolled away from the fire, there is a threaded bar which carries the meat away when it is rotated. On the turning shaft, there are four spur gears. On the bars carrying the meat, there is the worm gear which causes the meat to rotate easily. In short, the only thing that the cook will need to do is to turn the motor on and using the levers fix the system he want to. More than one system can turn. That is, the meat could be rotating and at the same time roll some pieces of meat away from the fire. Materials and components choosing The common material in the system is the mild steel. This is because it is cost effective and can endure high stresses; both heat and tensile. Flat belts are the best suited because of the use of lever. Flat belts are easy to replace and work well though slipping is high. The material used for belts should contain some traces of glass fibre to endure the much heat present when the roasting is being done. Disposal and recycling Steel is a very common metal in the engineering work. The materials made from steel may not last a life time but the steel itself can last for several decades. The design on the spit roast mainly consist of steel which can be recycled again and again. Some of the rods bars and beams can be re used before recycling. Even if steel would be left without reusing or recycling, it would eventually wear off due to rusting when there is water present. So even if it is not recycled, steel is biodegradable. The only type of steel that would take time to degrade is stainless steel which is very expensive. The entire mechanism is made of steel. It is only the base and some beams which would be of wrought iron. Due to high amount of temperatures, few materials can survive heat. Repair and replacement The parts used for this design are extremely simple to replace and repair as well. The design itself is simple and simple components and parts are equally simple and easy. Standard parts are used so that to finding a replacement is easy. Beams and bars can be easily recast. Pulleys employed here are also of a standard module which can be found in the market. Due to its simplicity, the spin roast system can be repaired by a layman. The simplicity of the system ensures that the maximum effort provided by human hand is sufficiently utilized. The replacement of the standard parts is equally simple. The essence of most of the design is that the system can be easily understood by a layman. If the system is too complicated, its operation may not be smooth and the person operating it may end up destroying the machine in the process of operation. The system reliability Steel is the most common metal in the planet earth. It has unlimited applications due to its properties which makes it withstand stress beyond which other metals could endure. It is for this reason that steel is used to make the bars upon which the roast is to hang. The frame of the system, the base and the turning mechanism are also made of steel. Its thermal properties make it endure intensive heat stresses it is subjected to in the process of roasting. When any metal is subjected to a lot of temperature variations, it expands and contracts distorting its geometry. The amount of distortion is a function of the thermal properties of the metal. Steel despite the expansion and contractions, it will serve its purpose for a very long time before replacement. The only parts which would be severely affected could the turning mechanism which is made of few pulleys. Steel has a very long life time. Its tensile strength as well as the ultimate yield strength are very high and can therefore be used as cantilever without failure. Effect of the environment on the components As stated earlier, steel is affected by moisture and therefore need to be enclosed so that it does not come into contact with water longer than it is necessary. It would therefore be very good if the system is enclosed by a polythene bag after the use so that the water from rain or from atmosphere would not have to reach steel. Painting would serve well, however, the high heat subjected to the system would make the steel wear off. It is therefore good to cover the system completely. When the steel rust, it does not produce harmful chemicals to the environment. The compounds are only iron III or iron II oxide. They dissolve into the soil and when accidentally consumed, they are harmless. This is not the case with some pvc products, which take long time to degrade and are affected by uv light. References Famularo, J. J. (1988). The joy of grilling. New York: Barron's. Pienaar, H. (2000). On the coals. Cape Town: Struik. Sullivan, M. (2012). How to roast a pig: The ultimate handbook for the perfect nose-to-tail backyard roast. Gloucester, Mass: Quarry. Read More