Text: Computer numerical control

Read the text, make up the annotation

Most CNC milling machines (also called 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 operators. 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.

Speaking

Exercise 5. Answer the following questions:

1) What is numerical control (NC)?

2) When were the first NC machines built?

3) What programs are used in modern CNC systems?

4) What devices have replaced the tapes?

5) What does parametric programming include?

6) What are CNC milling machines?

7) How many and what axes can CNC machines have?

Exercise 6. Prepare the oral report on the topic “CNC machine tools”.

Библиографический список

1. http://nptel.iitm.ac.in/courses/webcourse-contents/IISc-BANG/Material%20Science/pdf/Lecture_Notes/MLN_09.pdf
2. http://en.wikipedia.org/wiki/Vanadium
3. http://www.history.com/encyclopedia.do?articled=215393
4. http://www.1911encyclopedia.org/Metal-Work
5. http://en.wikipedia.org/wiki/Borazon
6. http://en.wikipedia.org/wiki/Alumika
7. http://en.wikipedia.org/wiki/Alloy-Steel
8. http://en.wikipedia.org/wiki/plain-carbon_steel
9. http://en.wikipedia.org/wiki/Tool_steel

10. http://en.wikipedia.org/wiki/High_speed_steel

11. http://en.wikipedia.org/wiki/Machine_tool

12. http://en.wikipedia.org/wiki/Drill#Drill_press

13. http://en.wikipedia.org/wiki/Lathe_(tool)

14. http://en.wikipedia.org/wiki/Screw_machine

15. http://en.wikipedia.org/wiki/Milling_machine

 

 

ДЛЯ ЗАМЕТОК

 

ДЛЯ ЗАМЕТОК

 

 

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