Shapes and Planers

The shaper (поперечно-строгальный станок) is used mainly to produce different flat surfaces. The tools slides against the stationary workpiece and cuts on the stroke, returns to its starting position, and then cuts on the next stroke after a slight lateral displacement. In general, the shaper can make any surface having straight-line elements. It uses only one cutting-tool and is relatively slow, because the return stroke is idle. That is why the shaper is seldom found on a mass production line. It is, however, valuable for tool production and for workshops where flexibility is important and relative slowness is unimportant.

The planer (продольно-строгальный станок) is the largest of the reciprocating machine tools. It differs from the shaper, which moves a tool past a fixed workpiece because the planer moves the workpiece to expose a new section to the tool. Like the shaper, the planer is intended to produce vertical, horizontal, or diagonal cuts. It is also possible to mount several tools at one time in any or all tool holders of a planer to execute multiple simultaneous cuts.

Grinder

Grinders (шлифовальные станки) remove metal by a rotating abrasive wheel. The wheel is composed of many small grains of abrasive, bonded together, with each grain acting as a miniature cutting tool. The process gives very smooth and accurate finishes. Only a small amount of material is removed at each pass of the wheel, so grinding machines require fine wheel regulation. The pressure of the wheel against the workpiece is usually very light, so that grinding can be carried out on fragile materials that cannot be machined by other conventional devices.

Exercises

Exercise 1. Find where in the text it is said about the points given below. Put down the number of a paragraph.

1. lateral displacement;

2. planer;

3. wheel;

4. conventional devices.

Exercise 2. Match the words on the left with their definitions on the right.

shaper planer grinder

is the largest of the reciprocating machine-tools; is the machine-tool removing metal by a rotating abrasive wheel is the machine-tool being used mainly to produce different flat surfaces.

Exercise 3. Answer the following questions. Find answers in the text. Put the number of the paragraph.

1. What is the shaper used for?

2. How does the shaper work?

3. Why is the shaper seldom found on a mass production line?

4. What is the planer?

5. What must be done to execute multiple simultaneous cuts on a planer?

6. What is the working tool in a grinder?

7. What is the wheel composed of?

8. Why do grinding machines require fine wheel regulation?

9. Can we grind fragile materials and why?

Exercise 4. Say if the following statements are true or false:

1. The shape can make any surface having straight-line elements.

2. The shaper is often found on a mass production line.

3. Like the grinder, the planer is in tended to produce vertical, horizontal, or diagonal cuts.

4. Grinders remove metal by a rotating abrasive wheel.

5. The wheel is composed of many large grains of abrasive, bonded separately, with each grain acting as a huge cutting tool.

6. Only a small amount of material is removed at each pass of the wheel, so grinding machines require fine wheel regulation.

Exercise 5. Describe the work of a shaper and a planer.

Exercise 6. Discussion points.

1. The difference and the similarity between the shaper and the planer.

2. The importance of the wheel application for grinders.

Text 3

Dies

Dies are tools used for the shaping solid materials, especially those employed in the pressworking of cold metals.

In presswork, dies are used in pairs. The smaller die, or punch, fits inside the larger die, called the matrix or, simply the die. The metal to be formed, usually a sheet, is placed over the matrix on the press. The punch is mounted on the press and moves down by hydraulic or mechanical force.

A number of different forms of dies are employed for different operations. The simplest are piercing dies (пробивной штамп), used for punching holes. Bending and folding dies are designed to make single or compound bends. A combination die is designed to perform more than one of the above operations is one stroke of the press. A progressive die permits successive forming operations with the same die.

In coining, metal is forced to flow into two matching dies, each of which bears a engraved design.