SOLIDWORKS DRAWINGS OF COMPONENTS OF A GEARBOX
PINION GEAR INPUT GEAR STAGE SHAFT OUTPUT SHAFT BALL BEARING CASING GEARBOX ASSEMBLY
ayushman dutta
INNOVATIVE METHODS IN SCHOOL TEACHING
From innovative, I would refer to some practises which are currently not enacted in school curriculum, but is already practised in other places. Surprise tests: The fear of exam is the most compelling reason behind taking the books out of those shelves. When students are introduced to surprise tests, this will be difficult since students would have to study everyday. A regular everyday study of atleast an hour is more productive than mugging up on the day before the exam. Compulsory extracurriculars: This is a rule in some schools while most of the remaining ones are yet to adopt the system. Chess clubs, quiz clubs, astronomy clubs, spellbee club, nature clubs, the list goes on. Not just clubs, students may also opt for sports. Basketball, football, hockey, badminton, cricket. Being in either a club or in any sports team should be mandatory. Subject Projects/ Essays: Projects in primary schools would mostly involve small thermocol models or it would involve us to write long essays. Instead of a single topic, students should be asked for a write up of all the chapters in the particular subject. Moreover, it would be better if the students are restricted to only the school library and computer lab for project work. With a fixed time and the school resources at disposal, it would be fair and equal for everyone. Cross teaching: This is a very interesting activity. A student is selected and asked to read a short story. Lets call it A. A second boy is asked to read short story B. Now they are made to sit facing each other. They have to explain their story to the other person within a given time. After this, the supervising teacher will ask them questions from the story they heard. Meaning Boy 1 will have to know story B perfectly and Boy 2 must know story A perfectly. This greatly improves teaching skills, listening skills understanding and quick learning. Counselling: This is really important. Psychometry tests and a routine evaluation of students is always helpful. Parents should be notified if there is anything that troubles the kids. Having said these, its not an easy task. Approval of parents as well as teachers play an important role. The end point is that the educational system should bring out the potential in a child, and not restrict his imagination. May have missed a lot of points, but these seemed to be the most innovative ones. Will update if I get more ideas!
DESIGN METHODOLOGY OF A SPRING LOADED RELIEF VALVE
DESIGN METHODOLOGY OF A SPRING LOADED RELIEF VALVE INTRODUCTION: In this CASE STUDY, a spring loaded safety relief valve has been designed based on a given problem statement. The design procedure involves the following: Designing of the SPRING to be used Designing of the THREADED FASTENER to be used for joint The spring loaded safety valve has been assumed to be an assembly consisting of a spring (to be designed). The assembly attached to a pipe joint using a flange. Based on the cracking pressure, the shape of the flange and the resulting no. of threaded fasteners have to be decided. Having decided the nature of the flange the dimensions of threaded joints must be decided. PROBLEM STATEMENT: A boiler safety relief valve, using a close coil helical spring is set to blow-off at a fluid pressure of 0.35 N/mm2. A suitable compression spring is required for the purpose. The valve diameter is 12.70 mm. Use a suitable spring constant. Maximum lift allowed is 5 mm and the initial compression in the spring is 10 mm. Maximum shear stress allowed for wire is limited as per the material of the wire. Find the necessary dimensions of the spring. The given valve is vertically attached to the top of a boiler with the help of a flange coupling using a certain number of bolts. Based on the working stress being subjected to the coupling, determine the bolt dimensions required for keeping the valve seated. GIVEN DATA AND ASSUMPTIONS MADE: Depending on the application (steam boiler), the following data has been gathered: Material selected= Carbon steel C= 6 τ= 294 MPa G= 80 kN/mm2 Max. pressure= 0.35 N/mm2 Valve dia=12.70 mm Bolt material= ASTM A36 (σt= 450 MPa) F.O.S =8 CALCULATION FOR SPRING: Given in attachment.
ENGINEERING DISASTERS I
ENGINEERING DISASTERS: THE RUSSIAN FLYING FORTRESS While Americans are renowned for wrapping up their works in the quickest ways possible, Russians follow a motto of “stay strong till you last”. Characterized by the robust nature of their engineering, Russians always believe that a machine should be judged by the number of years it lasts and not the performance. At a time when scientists all around the world were engaged into miniaturization, Russians still thought that “Big is the way”. Back then during WWII, aircrafts were designated based on their purpose in a battle. There were bombers, cargo aircrafts, reconnaissance, fighters and what not. The need for a multipurpose flying machine was a big matter. So the Russians came up with the idea of an aircraft that would cater to all these needs together. The failure of the Russian K-7 Flying fortress is a classic example of the fact that addition rule does not work out during all situations. It means that taking out the individual perks of all the aircrafts and assembling them into a single one with hopes of churning out the maximum level of destruction is not a good idea. Altough it took decades to realize, aircraft engineering itself was at a nascent stage and experimentations were still at large. The fortress was a very product of this addition rule. It was an amalgamation of every category of weaponry one can think about. It could have been named as a “machine gun with wings”. To talk about the specs of the aircraft, this gigantic monster was a nightmare for its enemies. The wingspan of the craft was a whooping 132.5 metres, a length which is almost double the length of a modern-day Boeing 747 aircraft. With an estimated cargo carrying capacity of more than sixty eight tonnes, it could practically carry tanks and armored vehicles. Imagine a tank being dropped from mid-air right into the middle of the battlefield. The fortress was to be propelled by as many as twenty propeller engines. The weaponry attached to the flying giant is what really made it a “giant”. The flying fortress had two heavy rail guns at the tail section of the fuselage. These two rail guns were further backed by a dozen gunner positions. As a strategic bomber, it had a housing capacity of 8.5 tonnes of droppable weight. Statistically more than a hundred paratroopers could have been accommodated at a time. It crashed, on the first attempt of takeoff itself. With a payload of much less than what it was designed for. Considering the size of the craft, it was not even possible to build another prototype!
IS THERMAL ENGINEERING DYING?
IS THERMAL ENGINEERING DYING? With the ongoing emergence of electrification of transportation around the globe, the future of thermal engineering looks bleak and uncertain. This has led to worried students pursuing the field into asking questions like “Is it okay to learn about IC engines when all vehicles will run on batteries by the next decade?” Though it looks like a dominant thermal market, electrification is indeed happening. Power plants, turbine based machinery, conventional engines, are they going to be there in the next few years? As a thermal engineering aspirant and also as a person who supports environmental betterment, I would like to state a few points on the matter. When such questions are asked, people tend to make a number of incorrect assumptions based on limited knowledge. Firstly, thermal engineering is a broad domain and encompasses much more than petrol and diesel run engines. Think about gas turbines. These mammoth giants use heat generated from coal and fossil fuels to rotate shafts that generate electricity. One cannot possibly electrify a gas turbine. The point intended to be stated here is that thermal machinery generate electrical power from conventional and non-conventional sources, and electrification of these machines do not make sense. The next point is that the subject not only deals with machinery but also the design of machinery for heat transfer. If you are a mechanical, heat transfer will be a relatable term. Nevertheless, it deals with the transfer of heat across surfaces like pi-pes, flat and circular plates, and other such components. A component in an industry, besides the forces being subjected to, also has to be designed on the basis of heat generated during operation. Take LiPo batteries as an instance. These batteries are the powerhouse of the electric vehicles, and in order to contain them, heat sinks and cages are used. These components are designed on the basis of the concepts of heat transfer. Similarly heat dissipation based components work on the basis of heat transfer. The misconception here is that people associate thermal sciences with the release of toxic pollutants which are detrimental to the ecosystem. It is indeed true; and the emission control norms have been established for the very reason. Just as people are considering electrification as an alternative; betterment of emission norms is also working towards zero emission technologies. However adherence to emission norms are not being taken as seriously compared to reduction of gaseous pollutants. Electrification, as the name suggests is on the verge on using electricity as a primary medium for harnessing mechanical energy. But there are quite a number of issues with them. To start with is the source of electric power: The LiPo battery. Disposal of these batteries is a worldwide concern and failing to dispose them in a proper manner does great harm to the surroundings. Such batteries need to be charged frequently; and the number of electric stations is relatively few compared to gas stations. Altough it is a problem, the number of petrol stations is expected to multiply across developed countries by the next few years. Net power output is another topic to be pondered. The efficiency offered for an electric vehicle for the same money is quite less than a petrol or diesel run automobile. On dividing the total money spent on charging and procuring battery packs by the number of miles it can run, the number is much less when this is done for conventional automobiles. Simply said, the money involved for running an electric transport for a single mile is way more than for a petrol based transport. On a concluding note, both of the developments are equally helpful. Electrification saves fuel; while fuel can be saved for more concerning uses like generating electricity. Fuel emission norms are to be acknowledged at an equal light as the conversion of transport to electricity. Thermal engineering is a vast field and has plenty of applications in our daily lives. It is always been helpful for the greater good of the society. One should not simply discard it as an age old topic that leaves little scope of improvement.
HOW WOULD YOU END UP IN A MECHANICAL INDUSTRY?
HOW WOULD YOU END UP IN A MECHANICAL INDUSTRY? As mechanical aspirants, the kind of jobs offered in the related industries is a burning question. “Core jobs” is a commonly heard phrase; but little do the students know about it. The idea of the work one may end up in any industry is crucial, as then the person can prepare himself accordingly. The primary explanation for core is a job profile where a person has to incorporate all the principles and concepts he learned in the subjects pertaining to the mechanical engineering domain. But it’s a big domain, and as a result a diverse number of jobs are available under the category of core. Before we delve into the types of job profiles, one must know that there are two types of mechanical industries: Public Sector Undertakings (abbreviated as PSUs) and private sector companies. Public Sector Undertakings have a detailed form of their job profiles, since they recruit graduates who have achieved a satisfactory score in the GATE examination. These job profiles are available on internet for aspirants. For example, ONGC has mechanical posts labelled as AEE, which are categorized into Cementing, Drilling, Production, Chemical, and Materials management. More light is shed upon their specific roles when a graduate is recruited for training. However, it gives an idea of what you are in for. Similarly BHEL has job profiles (for the mechanical graduates) which are segregated into thermal, production, tooling, industrial, thermal and mechatronics. The labelling of the positions gives a sense of direction where an aspirant should proceed, provided he is interested in pursuing such jobs. Coming to the private sector firms, the primary sources of recruitments are either campus selections or online applications through platforms such as naukri.com. In such cases, a detailed job profile is provided. The complete form consists of the prerequisites in skills and educational qualification, the job profile, the preference of locations for postings and the CTC offered. Based on this, one can decide if the job would be suitable or not. Due to lots of private sectors, all having varying fields of works, it is difficult to categorize them into a single system. There may be a unique job in a certain industry which is not present in the other private sectors. The department names vary based on industries. Every company has a specialized hierarchy to suit their interests. Marketing is the first part of any mechanical industry. Marketing and sales people talk to potential customers, make a list of the specifications they want, convey the capabilities of the industry. Marketing department provides the resulting problem statement to the design department. Design and research is often pit together as a single department. And often it is not. This department is responsible for making an entire design of the machine based on the demand specified by the customer. A department termed as Material handling handles the raw materials required for the complete manufacturing, charting out and outsourcing (fully or partially). The raw materials are procured and handed to the manufacturing department, who wait for the process planning department for instructions. Process planning succeeds the design stage. This involves the 2D draughts and drawings being sent to process planning department. For every component and sub assembly, there is a sequence of manufacturing operations are underlined. Manufacturing is one of the few of them which are not a single department. It is subdivided based on the type of company. For example, a gearbox company has two parts of manufacturing: turning, hobbing and grinding. The manufactured components are sent to the Assembly department. Here the components manufactured by the manufacturing section are first heat treated. It is a whole array of processes including case carburizing, nitriding and more. Post heat treatment, these are sent for final assembly. The concluding step is the Quality Inspection. The final assembly is inspected and tested under loading conditions to see if it is running without any issues. This is a general sequence of complete operation carried out in an industry. There may be extra added department. There is a special analysis department present in some industries, which are responsible for software simulations and comparing to actual results. There is a material quality inspection department in some industries. The raw materials procured are tested and their mechanical properties, impurities present if any, are seen. Every department has something unique to offer and demands a person opting for it to have a specific skill set. Having a preliminary knowledge of these jobs helps in understanding where the person should excel in order to bag the role. It is as they said: knowing your opponent is halfway towards winning the war and this is no different. Last but not the least, I urge students to go through job roles offered in private sectors. These profiles are available in any online job portals like Naukri and Glassdoor. It would be a more enlightening experience.