Forging Processes (I)

Forging is the process by which hot metal is shaped by hammering to the desired shape. An essential part of the process is to bring the metal to the correct heat in the hearth and to form it quickly and efficiently before the working heat is lost. For this reason the equipment used in forging will be positioned close to the hearth so that there is little delay between removing the metal from the hearth and working it. Tongs are used to hold the hot metal whilst it is being worked and a variety of tongs are required to hold the different shapes and cross-sections of stock material securely. The anvil, leg vice and swage block are essential items of equipment placed around the hearth and it is on these that metal is hammered, bent and formed.

The working heats of the metals used for forging are judged by the colour of the hot metal and it is only with experience that these can be accurately assessed. However, a general guide to the working heats of mild steel and wrought iron would be:

Red Heat	Allows simple bends in mild steel
Cherry Red Heat	Allows simple forging operations in mild steel
Yellow Heat	All forging operations in mild steel and wrought iron
White Heat	Allows the welding of joints in mild steel and wrought iron

Forging a taper

The forging of a tapered end in round or square stock is a common process and the stages are shown in the diagrams opposite.

1. With the metal at yellow heat the end is hammered on the face of the anvil to flatten the end.

2. Hammering is continued with the bar or rod turned through 90 degrees to produce a blunt point.

3. After reheating the metal is hammered from the end, working along the length of taper required. Square stock is hammered on each of its four sides but round stock is shaped to an octagonal section.

4. Further hammering is carried out to achieve the required point and length of taper. In this final stage the corners of the octagon on round stock will be hammered to the round.

It is important to work from the end of the material as described above to prevent the formation of a hollow, or 'piped' end.

Upsetting

Upsetting, or jumping up, is a method of increasing the sectional size of a bar at its end or at a point along its length to provide extra material. It should be noted that when a piece of stock is upset there will be a loss in length and this must be allowed for. The area to be upset is heated locally to a yellow heat, the heated zone being restricted by quenching (pouring water) onto the surrounding metal. With the bar standing on the face of the anvil hammer blows are deliver­ed to the top of the bar, causing the heated section to spread, as shown opposite. Upsetting is always necessary when a square bend is to be made in a bar and the stages in making such a bend are shown in the diagrams.

1. The bar is upset in the correct position for the bend.

2. The upset section is hammered on the face of the anvil so that the extra material is moved to the outside of the bend.

3. The bend is made by hammering the metal over the corner of the anvil.

4. The corner of the bend is shaped by hammering the extra material to a square corner.

Bending an eye

An eye can be formed by hammering the metal over the bick of the anvil. Care should be taken not to flatten or distort the metal by hammering unnecessarily hard. As shown in the diagrams the stages in bending an eye are:

1. Firstly a length of the bar or rod which equals the circumference of the eye is heated and bent to a right angle over the corner of the anvil.

The curve of the eye is then started by hammering the end over the anvil bick, making sure that the hammer lands in advance of the point of contact between the metal and the bick.

2. The next section of metal is heated and hammered to extend the curve.

3. The final length of metal is heated and hammered to complete the rough forming of the eye.

4. The eye is finally heated and closed by hammering down the end onto the anvil bick. If necessary the eye can be flattened by striking it down onto the anvil face.

Bending

Heated metal can be bent without hammering by pulling it around metal formers held in a vice or with the use of bending jigs, to ensure uniformity when making a number of bends to the same shape. Shown opposite is a jig in which metal formers can be bolted to shape the inside of a bend. The metal is heated locally and pulled around the former, being held in place by the vertical post to make the required bend.

Twisting

The twisting of square or rectangular sectioned bar is often used to strengthen and decorate a length of material. Twisting is usually carried out with one end of the bar held in the vice using a wrench made of flat bar to turn the material through 90, 180.270 and 360 degrees. It is important to ensure that the length of material to be twisted is heated to a uniform heat. When making equal twists in metal length a tubular sleeve can be used to gauge the length of twist and to keep the metal straight.

II. Answer the following questions: (Score – 3 points)

1. What are the stages of forging a taper?

2. What does the process of upsetting mean?

3. What other forging processes do you know?

III. Choose the Ukrainian equivalents from the box. (Score – 10 points)

1. tongs; 2. hammering; 3. bend; 4. quenching; 5. blunt; 6.to distort; 7. to turn; 8. upsetting; 9. eye; 10. bick

a) отвір, глазок; b) накувальня; c) згин; d) тупий; e) руйнувати; f) розкування, висадка; g) гартування; h) виточувати; i) кліщі, щипці; j) кування, ковка

IV. Point out which of the sentences below contains the information related to the text. (Score – 10 points)

1. London University, which is the biggest one in England, has a large number of various colleges.

2. This form must be completed in duplicate and two recent photographs attached.

3. Tongs are used to hold the hot metal.

4. The working heats of the metals used for forging are judged by the colour of the hot metal.

5. Square stock is hammered on each of its four sides.

6. We know that the entrance exams of English Universities are very strict.

7. If you want to make a square bend in a bar you should use upsetting.

8. If you come to the University on Monday you will hear a lecture about the latest achievements of Forging.

9. You must be careful not to flatten or distort the metal by hammering too hard.

10. The equipment is in great demand even at this price.

V. Tell about the working heats of the metal used for forging. (Score – 6 points)

(Total Score – 64 points)