Laser Welding

Laser are now being used in the automotive industry to produce seam or stitch welds, as alternatives to conventional resistance spot welding, which are used extensively for attaching auto body panels to sub-assemblies.  The advantages of laser welding over resistance spot welding result from the smallness of the laser spot size, the large penetration depth of the weld into the material and the requirement that only single-sided access to the work piece is necessary. Further, the equipment used to carry out the welds can be easily adapted to new vehicle program changes, unlike that used for resistance spot welding. Potential benefits realized by the application of laser welding includes reduced flange widths, increased structural strength and high speed automated processing. Traditionally CO2 lasers have been used for auto body applications. Recent advances have been made with Nd:YAG lasers, which are now capable of producing beam powers of more than 2 kW or more through a fiber optic cable. This is particularly useful for robotic operations, where it is necessary to manipulate the laser beam about a stationary part. laser are also used in the manufacture of tailored blanks, where suitably prepared sheet metal, including differing thickness and  material combinations are butt welded together prior to being pressed into the finished shape. This results in considerable cost and weight savings and increases structural rigidity.

Although at present steel is the main material used in the vehicle manufacturing industry, the use of lighter materials, such as Al, Mg and Ti will in the future become of increasing importance, in order to reduce weight. This, however will require the ability to make satisfactory joins between these materials and steel. Aluminium alloys are invariable less weldable than automotive sheet steels due to its high diffusivity  and the presence of passive oxide layers, which have a significantly higher melting temperature than the base alloy and often a poor electrical conductivity. Laser welding of Al alloys is also problematic due to its high thermal conductivity and high reflectivity of the laser light, but progress is being made using Nd:YAG lasers.

There are number of different laser welding systems available. CO2 and Nd:YAG lasers are already in use in industry. Low power Nd:YAG lasers are used in the electronics industry Rapid improvements in technology means that diode lasers of sufficiently high power and power density for the production of good deep penetration welds are now available.

Laser Welding Process

When welding with laser beam, it is necessary to differentiate between two forms of welding: heat conduction welding and deep penetration welding. Conduction welding occurs at lower power densities or higher welding speeds. The absorbed energy is transferred by heat conduction into the volume of the work piece and produced a broad, shallow pool of molten material.

 In deep penetration welding, the laser beam is focused to a small spot and the power can exceed 5*10^6 Watts/m^2. Sufficient energy is input to vaporizer the material and a vapour-filled channel is formed through which the laser energy penetrates deep into the work piece. Deep seams are produced which increase the absorption efficiency and make greater use of laser beam. The energy required to melt and vaporize the material depends on the physical properties of the material, the wavelength of the laser light and the properties of the surface of the work piece. These welds typically have deep, narrow weld profiles, a small HAZ and little distortion. As a result of the better energy utilization and large depth to width ratio of weld is attainable with deep penetration welding, this is the prime method of welding used in industry with the conventional laser sources.    





 

Surface Tension Transfer (STT)

For many years pipe fabrication have been searching for a faster,easier method to make single-sided low hydrogen open root welds. It is difficult even for skilled welders to weld open root pipe and inflexible positioning makes pipeline welding more difficult, time consuming and expensive.

Higher Strength pipe steels are driving a requirement to achieve a low hydrogen weld metal deposit. GTAW has been only available process capable of achieving the quality requirements but GTAW root welds are very expensive to make. The GMAW process has been avoided because of side-wall fusion and lack of penetration.

Lincoln Electrics has developed and proven the Surface Tension Transfer process to make single-sided root welds on pipe. STT is a patented controlled short-circuit transfer GMAW process made possible by Linchon Electrics exclusive waveform control technology.
STT produces a low hydrogen weld deposit and makes it easier to achieve a high quality root weld in all positions. The STT process as a field proven quality record. STT eliminates the lack of penetration and poor sidewall fusion problems encountered when using the traditional short-arc GMAW process.

Advantages:

Penetration control: Provides reliable root pass, complete back bead and ensured sidewall fusion

1. Cost Reduction: Use 100% CO2 the lowest cost gas, when welding carbon steel

      2. Flexibility: Provides the capability of welding  stainless steel,alloys and mild or high strength                                steels without compromising weld quality

      3. Low heat input: Reduces burn through, cracking and other weld defects.

      4. Low hydrogen weld metal deposit: Hydrogen levels meet the requirements for use on high                                                                           strength pipe steels

      5. High quality open root welds at faster rate travel speed than GTAW

      6. Allow operator to control the heat input into the weld puddle

     7. Its easy to operate.

Technology in Welding

Developments in welding technology applicable to the industry are described in three broad themes; advanced arc welding, friction stir welding and laser processes. In each case, selected advances are reviewed and potential applications and benefits in offshore engineering are presented.

Introduction

Welding is a fundamental technology in the fabrication and repair of virtually all structures in the offshore industry, whether they be above or below sea level, or onshore. It is an enabling technology without which  the offshore industry (and many other industries) could not operate ai its present level of sophistication, and yet welding technology often sits in the background, taken for granted as a mature and established technology. Like most technologies, it is developing steadily over time, allowing new benefits in terms of what can be achieved, and in terms of process economics.

The topic will be about the recent developments in a selection of welding processes which may have potential for use in the industries.

1. Advanced Arc Welding 
2. Friction Stir Welding 
3. Laser Welding     

Pre- Crash Sensors for Pre-Crash Safety(part 2)

Many research and development have been conducted  to meet society needs for safer vehicles. Particularly, occupant protection system such as air bags, developed and introduced in order to reduce occupant injuries in crashes, are currently installed in most vehicles making significant contribution to safety.

Meanwhile, many studies have been made into the development of active safety technologies that help to avoid crash accidents. Unfortunately the current situation is that the active safety technologies are not sufficient spread. Adaptive cruise control has been commercialized since 1995, but its primary use has not been convincing.Some audible warning system  are also being offered, but have not yet reached widespread use.

Toyota Motors corporation has explored the possibility of producing an active safety system employing Intelligent Transport System (ITS) technologies,through participation in the Advanced Safety Vehicle (ASV) projects started in 1991 and led by ministry of land , infrastructure and transport.

Critical basis ITS technologies for application to ASV includes a surround monitoring sensor and an obstacle determination algorithm which combines information from the surround monitoring sensor with other information to identify obstacles with which the vehicle is likely to actually crash.

The sensors and crash determination algorithm for an active safety system should be capable of reliably determining that  a crash will not occur in non-crash situation. Advanced technologies are required to make these predictions and judgments correctly while also taking into account the driver's operation and behavior and this has hampered widespread of active safety systems.

Pre-crash safety system has been developed which operates only when it is judged that a crash cannot be avoided by most drivers under normal driving conditions. Determining unavoidable crashes is restricted to a short time period immediately before the crash so as to improve the reliability of the judgement. In addition the pre-crash system is made with a mechanism and system that will not place the driver and the running vehicle in an unsafe condition even if the system is operated unnecessarily. As a result the world's first commercial system has been achieved.

mechanical views: PRE- CRASH SENSOR FOR PRE-CRASH SAFETY Part 1

mechanical views: PRE- CRASH SENSOR FOR PRE-CRASH SAFETY Part 1: Improvement of vehicle safety performance is one of the targets of the ITS development.A pre-crash safety system has been developed that ut...

PRE- CRASH SENSOR FOR PRE-CRASH SAFETY Part 1

Improvement of vehicle safety performance is one of the targets of the ITS development.A pre-crash safety system has been developed that utilizes ITS technologies. The pre-crash safety system reduces collision injury by estimating TTC (time-to-collision) to preemptively activate safety devices, which consist of "pre-crash seat belts" system and "pre-crash brake assist" system.

The key technology of these systems is a "pre-crash sensor" to detect obstacles and estimate TTC. The pre-crash Sensor uses millimeter-wave radar to detect preceding vehicles, oncoming vehicles, roadside objects, etc. on the road ahead. Furthermore, by using a phased array system as a vehicle radar for the first time, a compact electronically scanned millimeter wave radar with high recognition performance has been achieved.

With respect to the obstacle determination algorithm, a crash determination algorithm has been newly developed, taking into account estimation of the direction of advance of the vehicle, in addition to the distance, relative speed and direction of the object.   

V2V (Vehicle to Vehicle) Communication

The objective of ambient intelligence is to create an intelligent daily space, which is immediately usable and integrated into our homes, our offices, our roads, our cars, and everywhere. This new concept must be invisible; it must blend in with our normal environment and must be present when we need it.

One of the application of this concept consists of providing our cars and roads with capabilities to make road more secure (information about the traffic, accidents, dangers, possible detours, weather, etc.) and to make our time on road more enjoyable (Internet access, network games, helping two peoples follow each other on the road, chat, etc). These applications are typical example of what we call an Intelligent Transport System (ITS) which goal is to improve security, efficiency and enjoyment in road transport through the use of new technologies for information and communication.

Traditional traffic management systems are based on centralized infrastructures where cameras and sensors implemented along the road collect information on density and traffic state and transmit this data to a central unit to process it and make appropriate decisions. This type of system is very costly in terms of deployment is characterized by a long reaction time for processing and information transfer in a context where information transmission delays is vital and is extremely important in this type of system. In addition, these devices on roads requires periodic and expensive maintenance. Consequently, for large scale deployment of this type of system, important investment is required in communication and system infrastructure. However, with the rapid development of wireless communication technologies, location and sensors, a new decentralized architecture based on vehicle to vehicle communications has created a very real interest in these last few years for car manufacturers, R&D community and telecom operators. This type of architecture relies on a distributed and autonomous system and is made up of the vehicles themselves without the support of fixed infrastructure for data routing.  

The main objectives of an intelligent transportation system includes:

1. the improvement of trip security
2. the improvement of global efficiency of the transportation system by reducing travel time and congestion
3. the integration of transportation in a durable development policy particularly by reducing gas emissions for light vehicles and heavy trucks and  by optimizing maintenance of the infrastructure
4. the improvement of user comfort by providing him with a selection of information, decision support, guidance and internet access services.

 

mechanical views: Automated Manual Transmission

mechanical views: Automated Manual Transmission: MT (manual transmission) uses simple spur gears providing excellent transmission efficiency and thus typically get 10% or better fuel milea...

Automated Manual Transmission

MT (manual transmission) uses simple spur gears providing excellent transmission efficiency and thus typically get 10% or better fuel mileage than current ATs (automated transmissions). The object of the ATM (automated manual transmission ) is to automate starting and gear shifting while retaining this excellent fuel efficiency. A round of fierce competition was triggered among European manufacturers to see who would be the first to develop what is generally known as a conventional AMT that attempts to automate the shifting of MT. The problem with this design is that the drive torque is momentarily interrupted during shifting. This results in a very different shift feeling from an AT, and thus never saw the wide spread acceptance as a replacement for the conventional AT in mainstream vehicles. This was more recently followed by a twin clutch AMT that is receiving great deal of attention. Supporting smooth and responsive shifting much like an AT, the twin-clutch AMT has been installed by European vehicle manufacturer on some high engine capacity sport cars beginning last fall. Hitachi group has now developed an original torque-assist AMT that is fundamentally different from these other two approaches.

TORQUE-ASSIST AMT

In order to achieve widespread acceptance as a replacement for conventional transmissions, the next generation must provide the good fuel economy of an MT, the effortless shifting of an AT, and must also be compact and affordable. Unfortunately, the conventional AMT fails to achieve the seamless shifting of an AT and the twin clutch AMT is difficult to implement compactly and cost effectively.

Hitachi Group has proposed a third way that does meet all the above requirements a torque assist AMT and is now in the process of developing this system. A key advantage of this approach is that it can be implemented with relatively little modification to existing AMTs by simple adding a friction clutch called as assist clutch to the transmission. Action of the assist clutch effectively solves the torque interruption  problem of the conventional AMT while providing the smooth gear shifting of an AT.  A compact and economical torque assist AMT could thus be implemented fairly easily for application on mainstream FF (front-engine front-drive) compact vehicles with engine displacement with 2 liters.

DRIVERLESS CARS

For generations, the automobile industry has been a source of innovation and economic growth. The ability to drive is a symbol of mobility and independence that spans generations. Clearly, automobiles play a significant role in our lives and afford many benefits to society.

Yet for all benefits conferred on society, no other invention in the history of civilian technology has caused as much harm as the automobile. Every 30 seconds. someone dies in a traffic accident, adding up to well over 1 million deaths each year. In the US automobile accidents are the leading cause of death for people between the age of 3 and 34. Moreover,human error is the cause of over 90% of automobile accidents.

In addition the inefficiencies related with the automobile usage is staggering. Most automobiles sit unused more than 95% of their life span, and a freeway operating at maximum  efficiency has automobiles on only 5% of its surface. In congested urban areas, 40% of all gasoline used is spent when car looks for parking spaces. Furthermore, in some US cities, parking lots comprise more than third of the land, becoming the single salient landscape feature of our built environment.

Since its inception of the commercial auto industry in the late 1890s, cars have become increasingly safe and convenient. Recently, car makers have begun to introduce advanced driver-assistance systems such as adaptive cruise control (which automates accelerating and braking) and active lane assist (which automates steering). These systems have become capable enough that new luxury vehicles can drive themselves in slow moving highway traffics. Research into autonomous cars has progressed remarkably since the first demonstrations in the 1980s. In 2010, four driver less vans traveled from Italy to China. In august of 2012, google announced that its self-driving cars had completed over 300,000 miles of accident free autonomous driving. Although self-driving cars may still seems like science friction, Google, many industry analysts, auto suppliers, and car makers project that such cars will be available before 2020.  

CNG in India

Compressed natural gas(CNG) is a fuel that needs no introduction.  it is a cheap fuel to make and use, which is why it is so widespread in public transport. Not to mention that the second hand car market is greatly supported by CNG kits. vehicles like the Honda Civic, Accord and Toyota Corolla are favorites to be bought second hand and then have green fuel kits used to make them easy on the pocket. With diesel deregulation soon to kick in, the price of the oil will head north soon, so CNG seems like a good investment for those with regular usage. here's the brief look at advantages and disadvantages of CNG:

Advantages:

1. it is the green fuel. the emissions and hydrocarbons that are released as the by product of CNG usage are lesser than those created by regular fuel. Carbon monoxide emission are down by 70-85% while hydrocarbon levels are reduced by 40-60%.
2. the price fluctuation of the natural gas is less. Look back over the past few years and you'll notice that petrol and diesel prices have been on roller coaster ride, but CNG has the relative linear movement. this is because of domestic production which has no dependency on international movements.
3. Engine life improves.Contrary to popular beliefs, CNG is a better fuel for improving engine life as the carbon levels are greatly reduced.

Disadvantages:

1. The performance of the car is reduced significantly. On an average CNG users experience a crash about 10% in performance. 
2. The storage space is eaten up badly. CNG tanks a easily the size of large bag, so boot space is reduced or removes entirely as the fuel storage tank takes up all the room.
3. Availability is not a wide spread as regular gas stations. Within the city users probably have a list of stations that falls in the route, but beyond that it is an uncertainty. This is the reason why cars aren't made to run exclusively on CNG.
4. Blocked injectors. Cars with CNG kits should always be started on petrol and run for few kilometers before being switched to the green fuel. This warms up the engine better and gets the motor well lubricated. Petrol is expensive so drivers often chose not to use it.
5.  Fuel range. Although CNG is a cheaper fuel, the actual range on just CNG is lesser than petrol. Not to mention, running on a close to empty tank reduces the pressure and increases the risk of valve bursting. So, even if the car uses CNG, it is always wise to keep a regular flow of petrol both in tank and in the engine usage.

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Desicant Cooling System

In the last 10 years, evaporative and desiccant cooling technology for air conditioning has increased as an alternative for air conditioning systems has increased as an alternative to the conventional vapour compression systems. A typical system combines a dehumidification system that uses a rotary desiccant wheel, with direct or indirect evaporative systems, allowing a filtered and cooled air supplying temperature, humidity and speed conditions that propitiate environmental thermal comfort, even in equatorial and tropical climates. These systems causes a lot of electrical power saving, mainly in place where thermal source energy source are easily found, where the price of electrical energy is high,where the latent heat percentage is high or where the needed air dew point is low. So, evaporative cooling systems that use absorption pre-dehumidification presents a great perspective in thermal comfort. It can be used in co-generation systems, where the needed heat to regeneration can be gotten from gas turbines exhaust gases or internal combustion engines or, still, from steam in plants that use steam turbine.

Experimental Analysis of an Air Washer

Hello World,

Today i will like tell you all about my 4th year project which was on the topic of experimental analysis of an air washer.
In the recent sanario the peoples are slowly getting conscious about the beast(pollution) intended to destroy our beautiful sphere(earth). This pollution had drastically spread in our world drastically in few years. It is sad to say but we are only responsible for it. The careless burning of fossil fuels, heavy growth in industries and inventions without considering about the earth safety pushed of us into this undesirable situation.

But now the peoples are thinking about what they are doing and what they had done including the government which taken so many steps for the control on pollution. The scientist's also get conscious about their invention which will be in the favor the reducing pollution.

  In India the refrigerants like R 22 is going to be banned in upcoming few years which is one of the major reason for the depletion of the ozone layer which causes global warming and some harmful skin disease's. These things created the requirement for the replacement of old cooling systems and introduction of the new inventions which are environment friendly.

My project was on the same concern me and my friends decided to try the project which can be the one of the substitute of the recent refrigeration system. On the suggestion of our professor we modified the air washer to not only work as an evaporative cooler but also can remove the sulphure dioxide from the air which is one of the gas responsible for green house effect.

In my project my team was using spray type air washer with the very simple design since it become easier to modify.

The spray type air washers consists of a chamber or casing containing a spray nozzle system, a sink for removing the spray water as it falls. And an eliminator section for the removal of moisture in the air. A pump recirculates water at the rate higher than the evaporation rate.

Intimate contact between the spray water and the air flow causes heat and mass transfer between the air and the water.
The air washer used in the industries has the basic use to clean air and control the properties of the air as per the requirement.

The air washer can perform two kinds of cooling:
1. Direct evaporative cooling
2.Indirect evaporative cooling

The direct evaporative cooling is done by the direct contact between sprayed water and the flowing air in the chamber.
Where the indirect evaporative cooling is done by providing heat exchanger at the front of air washer.
The syphon present in the heat exchanger is circulated by the cold water and the hot air is passed through the fins of the heat exchanger. Which causes heat exchange between air and water.

The indirect evaporative cooling was done in my project by the use of car radiator.

AIR WASHER SPECIFICATIONS

BLOWER

suction blower with 1HP, 3PHASE, 440 V and internal diameter 4 inch

NOZZLE SECTION

the nozzle section consist of:-

1. 4 elbow joints (0.5 inch bore)
2. 3 distributors (0.5 inch bore)
3. 10 vertical pipes (0.5 inch bore & 50 cm length)
4. 10 holes on vertical pipe each (1 mm bore)
5. 5 holes on horizontal pipe each (1 mm bore)

All the components in the nozzle section are made up of PVC material.

The body of the air washer was made up of the aluminium composite pannel. 
Two layers of simple cellulose pad was use in the eliminator section to absorb the moisture in the air.

The picture above will give you the brief and real understanding of the project.

The analysis was done with the following aims:
1. circulating the water at normal temperature and analyzing the changes in the property of the air
2. circulating hot water through air washer and analyzing the change in the properties of air
3. circulating chilled water through air washer and analyzing the changes in properties of air

I am providing some videos of working of my project i hope you will like it.

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introduction

Hello world,

This is saurabh kumar tiwari a mechanical engineer.
I made this blog to give you all the continuous updates about the activites happening in the mechanical sector and their possible effect on the global market.

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