04-10-2012, 05:03 PM
Multi Leaf Spring
INTRODUCTION TO LEAF SPRING
Originally Leaf spring called laminated or carriage spring, a leaf spring is a simple form of spring, commonly used for the suspension in wheeled vehicles. It is also one of the oldest forms of springing, dating back to medieval times. Sometimes referred to as a semi-elliptical spring or cart spring, it takes the form of a slender arc-shaped length of spring steel of rectangular cross-section. The center of the arc provides location for the axle, while tie holes are provided at either end for attaching to the vehicle body. For very heavy vehicles, a leaf spring can be made from several leaves stacked on top of each other in several layers, often with progressively shorter leaves. Leaf springs can serve locating and to some extent damping as well as springing functions. A leaf spring can either be attached directly to the frame at both ends or attached directly at one end, usually the front, with the other end attached through a shackle, a short swinging arm. The shackle takes up the tendency of the leaf spring to elongate when compressed and thus makes for softer springiness.
Eye rolling of main blade
The master blade is heated at its two ends for eye formation, these are done to attach with the frame of the vehicle. The heating is done in a end heating furnace
at a temperature of 1000 degree centigrade. The heating is done only at the ends so that it will be easy to bend at the ends. Furnace oil and the air are used for heating the furnace. The furnace is first allowed to heat freely for 45 mins. Now the master blades are placed in the furnace such that only ends are heated. After heating is done for one end it is bend to form the eye and again it is placed in the furnace to heat the other end. After heating the main blade is bent slightly to form curve at the end with the help of 50 ton punching machine so that it will be easy to roll to form eye formation. In the eye rolling machine the master blade end is placed between the circular wheel and the die. after placing the hand lever is moved so that the end of the master blade rolls over the die thus forming eye shape.
Industrial Defined Problem
Analysis:-
For the manufacture of laminated springs it is extremely necessary that the springs have enough strength to suffer the fatigue load. Fatigue load is the repeating load on the body. To achieve this we need to Harden the springs. In hardening, the leaves are heated at around 900 – 1000 degree Celsius temperature. Hardening involves the rapid cooloing of leaves which is called quenching. Quenching is done in the quenching oil. So due to instant cooling the upper surface of the leaves get eroded and forms scrap. The scrap is burnt iron due to heating at high temperature.
I went to many local casting and other metal alloys company to ask if the scrap could be of their use. But it was not of their use . They recommended me to ask some scrap traders if they could use it for further reprocessing.
The thing is this scrap can be recycled by casting it but who would do this. In a foundry, the raw material is in the form of large iron pieces. Also the monthly scrap of this company is 6000 kg (6 tonnes) which is less as compared to the raw material requirement of the foundry. Hence why would a foundry take this scrap ?
Suppose a foundry requires 500 tonnes of raw material and if it takes 6 tonnes of our scrap than still they need 494 tonnes . So instead of taking 6 tonnes which is very less for them they would prefer to buy whole 500 tonnes from other way.
So. I went to many local scrap traders but they refused to buy. The reason was that the scrap is separated along with the quenching oil.So for them it was a tedious job to separate the ferrous material from the oil. Also the ferrous material is a burnt iron. I contacted around 8 – 10 traders but the answer was same.Still I have shown the samples to some of the traders and waiting for their answer. Even I have fixed an appointment with a Ahmedabad Scrap Trader. He would analyse the sample and then reply for the same.
INTRODUCTION TO LEAF SPRING
Originally Leaf spring called laminated or carriage spring, a leaf spring is a simple form of spring, commonly used for the suspension in wheeled vehicles. It is also one of the oldest forms of springing, dating back to medieval times. Sometimes referred to as a semi-elliptical spring or cart spring, it takes the form of a slender arc-shaped length of spring steel of rectangular cross-section. The center of the arc provides location for the axle, while tie holes are provided at either end for attaching to the vehicle body. For very heavy vehicles, a leaf spring can be made from several leaves stacked on top of each other in several layers, often with progressively shorter leaves. Leaf springs can serve locating and to some extent damping as well as springing functions. A leaf spring can either be attached directly to the frame at both ends or attached directly at one end, usually the front, with the other end attached through a shackle, a short swinging arm. The shackle takes up the tendency of the leaf spring to elongate when compressed and thus makes for softer springiness.
Eye rolling of main blade
The master blade is heated at its two ends for eye formation, these are done to attach with the frame of the vehicle. The heating is done in a end heating furnace
at a temperature of 1000 degree centigrade. The heating is done only at the ends so that it will be easy to bend at the ends. Furnace oil and the air are used for heating the furnace. The furnace is first allowed to heat freely for 45 mins. Now the master blades are placed in the furnace such that only ends are heated. After heating is done for one end it is bend to form the eye and again it is placed in the furnace to heat the other end. After heating the main blade is bent slightly to form curve at the end with the help of 50 ton punching machine so that it will be easy to roll to form eye formation. In the eye rolling machine the master blade end is placed between the circular wheel and the die. after placing the hand lever is moved so that the end of the master blade rolls over the die thus forming eye shape.
Industrial Defined Problem
Analysis:-
For the manufacture of laminated springs it is extremely necessary that the springs have enough strength to suffer the fatigue load. Fatigue load is the repeating load on the body. To achieve this we need to Harden the springs. In hardening, the leaves are heated at around 900 – 1000 degree Celsius temperature. Hardening involves the rapid cooloing of leaves which is called quenching. Quenching is done in the quenching oil. So due to instant cooling the upper surface of the leaves get eroded and forms scrap. The scrap is burnt iron due to heating at high temperature.
I went to many local casting and other metal alloys company to ask if the scrap could be of their use. But it was not of their use . They recommended me to ask some scrap traders if they could use it for further reprocessing.
The thing is this scrap can be recycled by casting it but who would do this. In a foundry, the raw material is in the form of large iron pieces. Also the monthly scrap of this company is 6000 kg (6 tonnes) which is less as compared to the raw material requirement of the foundry. Hence why would a foundry take this scrap ?
Suppose a foundry requires 500 tonnes of raw material and if it takes 6 tonnes of our scrap than still they need 494 tonnes . So instead of taking 6 tonnes which is very less for them they would prefer to buy whole 500 tonnes from other way.
So. I went to many local scrap traders but they refused to buy. The reason was that the scrap is separated along with the quenching oil.So for them it was a tedious job to separate the ferrous material from the oil. Also the ferrous material is a burnt iron. I contacted around 8 – 10 traders but the answer was same.Still I have shown the samples to some of the traders and waiting for their answer. Even I have fixed an appointment with a Ahmedabad Scrap Trader. He would analyse the sample and then reply for the same.