Question 1

Continuous casting is more important than any other casting of steel because of several reasons that follows:

For example we can refer to the ingot casting. In ingot casting the molten steel is poured into larger molds compared to continuous casting. Then the ingots are placed in tightly covered soaking pits. The pits are heated in order to raise the temperature of the ingot. The ingots are rolled to the desired shape in a primary rolling mill. It may require more time in the soaking pits to achieve the correct uniform temperature throughout the ingot. The total time required, from ingot casting to rolling of the semi-finished shape (slab, bloom or billet) can be seven or more hours.

The continuous casting process skips all these separate steps of ingot casting, mold stripping, heating in soaking pits and primary rolling with just 1 operation. In certain cases, continuous casting also replaces reheating and rerolling steps. The molten steel solidifies from the outer cooled surfaces inward during the casting process. So that finally a fully solid slab, bloom or billet is produced. Clearly, long production runs of a particular product are made easier and more efficient with continuous casting.

Figure 1.1: Typical Continuous Casting Process

The main benefits of continuous casting over there casting are:

Considerable better energy savings, improved labor productivity (output), improved quality of the steel and finally reduced pollution.

Energy Savings and Increased Yield. Continuous casting process saves energy directly through the elimination of energy intensive steps. The elimination of soaking pits, reheating furnaces and primary rolling mills reduces the consumption of fuels (natural gas, oil and in-plant by-product gases) and electricity. In Japan, where one half of all steel is produced by the continuous casting process, the direct energy saving is about 50% of that used in ingot casting.

Improved Labor Productivity The increase in labor productivity with continuous casting results from elimination of the many steps of ingot casting, all of which demand direct labor input.

Improved Quality of Steel Most industry personnel report an improvement in quality of some continuously cast steels. The reduced number of steps and greater automatic control of the process both lead to fewer defects in the steel. There have been steady improvements in the process, particularly in the production of slabs for flat products requiring high surface quality.

Reduced Pollution It is generally recognized that continuous casting reduces pollution. The soaking pits and reheating furnaces are eliminated; less energy is required; reduced energy requirements leads, to less pollution produced. Hot steel is exposed to the atmosphere for a shorter time, producing fewer particulate.

Figure1.2: Continuous Casting in Industry.

Question 2

Parts of the car which involves a sheet metal forming process.

Car Door:

It’s all starts with carbon steel, an alloy that is strong n malleable. Machinery uncoils and straightens the sheet metal. Then large blade slices it to desired lengths producing sheets called blanks. These sheets undergo a press which is called hydroforming. The press forces the blank to a die giving it a basic shape of two car doors. Next and automated device with fingers then grips the newly shaped steel and transfers it to a punch cutter which separates the two doors and removes the excess unwanted metals. Figure 2.1 shows the car door after the hydroforming process.

Figure 2.1

Shock absorber

The shock absorbers 2 tubes, the outer one are the reserve tube and inside it the pressure tube that houses the piston rod and compression valve. Both of this tube is made of steel sheet sliced into stripes. Inside the tube mill cooling prevents the passing strip from overheating as the sheets undergo rolling by 1 forming roller after another gradually rounds it into a tube. Then a copper welding wheel fuses the tube closed. At last the cutting tool cuts the rolled tube into shock absorbers length. Figure 2.2 show the sheet metal undergoes a few rollers until it gets the round shape.

Figure 2.2

Fuel tank

It all starts with steel sheet which is nickel-plated to make the tank rust resistance. It is placed in a hydraulic press that applies 800 tons of pressure. This compresses the sheet between 2 dies. The press forces the male die up against the sheet and into the cavity of female die. To make the top part of the tank or different type of tank they simply change the die. On the top of the tank the stamping press imprints information such as the product and lot number and the manufacturer’s name. A hydraulic punch then punches 2 holes 1 for the tube to fill the tank and the other to vent it. Two metal wheels compresses the 2 sections of the tank together and water cools the area as the machine called the seam welder fuses the upper and lower half of the tank. Figure 2.3 shows the fuel tank after the press forming process.

Figure 2.3