IV. Comprehension.

Ex.10. Agree or disagree with the following statements:

1. The base, hollow inside, contains a heating tank with cutting fluid.

2. The outlet nozzles can be swivelled for distributing a low pressure volume of cutting fluid to all diameter and types of cutters.

3. A set of change gears for driving the spindle at a proper speed is housed in the lower part of the column.

4. The change gears are shifted automatically without an operator.

5. An elevating screw is used for adjusting workpieces with respect to cutters.

6. Vertical spindle machines are opposite to plain milling machines, but their spindle is positioned horizontally.

7. Universal milling machines are similar to plain milling machines but the saddle is mounted on and swivels on a clamp bed.

Ex.11. Answer the questions:

1. What is milling?

2. What are the main types of milling machines?

3. What does the base of the plain milling machine serve for?

4. By what means can the cutting fluid flow be regulated?

5. What is located in the lower part of the column?

6. What is secured to the top of the column?

7. Where is the knee mounted?

8. By what means can the knee be moved up and down?

9. What do cutting speeds on the milling machine depend upon?

Ex.12. Fill in the tables

a

Milling machines

)

classes

column and knee machine

styles

b)

horizontal milling machine

application

structure

V. Oral practice.

Ex.13. Speak on the topic “Milling machines” using the tables Ex.12.

Ex.14. Explain the similarity and the difference between the vertical spindle machines and universal milling machines.

VI. Reading and comprehension.

Ex.15. Read the text B without a dictionary for 6 min and say what problems are mentioned in the text.

Text b Computer numerical control

Thin wall milling of aluminum using a water based coolant on the milling cutter

Most CNC milling machines or machining centers are computer controlled vertical mills with the ability to move the spindle vertically along the Z-axis. This extra degree of freedom permits their use in diesinking, engraving applications, and 2.5D surfaces such as relief sculptures. When combined with the use of conical tools or a ball nose cutter, it also significantly improves milling precision without impacting speed, providing a cost-efficient alternative to most flat-surface hand-engraving work.

Five-axis machining center with rotating table and computer interface

CNC machines can exist in virtually any of the forms of manual machinery, like horizontal mills. The most advanced CNC milling-machines, the 5-axis machines, add two more axes in addition

to the three normal axes (XYZ). Horizontal milling machines also have a C or Q axis, allowing the horizontally mounted workpiece to be rotated, essentially allowing asymmetric and eccentric turning. The fifth axis (B axis) controls the tilt of the tool itself. When all of these axes are used in conjunction with each other, extremely complicated geometries, even organic geometries such as a human head can be made with relative ease with these machines. But the skill to program such geometries is beyond that of most humans. Therefore, 5-axis milling machines are practically always programmed with CAM.

With the declining price of computers, free operating systems such as Linux, and open source CNC software, the entry price of CNC machines has plummeted. For example, Sherline, Prazi, and others make desktop CNC milling machines that are affordable by hobbyists. High speed steel with cobalt endmills used for cutting operations in a milling machine.

Notes:

engraving- гравіювання

relief- рельєф

decline- зменшуватися

plummet- збільшуватися

Ex.16. Render the text B using the plan for rendering.