17. What is grinding temper burn? What is grinding and quenching burns? What is grinding annealing burn?

Tempering: If the temperature in the grinding zone does not exceed the phase transformation temperature of the quenched steel, but exceeds the transformation 

temperature of martensite, the martensite of the metal on the surface of the workpiece will be transformed into a tempered structure with lower hardness. Quenching: If 

grinding The temperature in the zone exceeds the phase transformation temperature, and coupled with the cooling effect of the coolant, the surface metal will have a 

secondary quenching martensite structure with a higher hardness than the original martensite; in its lower layer, the hardness will appear due to slower cooling. Annealing 

of a tempered structure lower than the original tempered martensite: If the temperature in the grinding zone exceeds the phase transformation temperature and there is no 

coolant during the grinding process, the surface metal will have an annealed structure, and the hardness of the surface metal will drop sharply.

18. Prevention and control of mechanical processing vibration

Eliminate or weaken the conditions that produce mechanical processing vibration; improve the dynamic characteristics of the process system, improve the stability of the 

process system, and adopt various vibration and vibration reduction devices.

19. Briefly describe the main differences and application occasions of machining process cards, process cards and process cards.

Process card: single piece small batch production using ordinary processing methods. Mechanical processing card: mid-batch production. Process card: large batch 

production type requiring strict and meticulous organization work.

20. What are the principles for selecting rough benchmarks? Principles for fine benchmark selection?

Coarse datum: 1. The principle of ensuring mutual position requirements; 2. The principle of ensuring reasonable distribution of machining allowance on the machined 

surface; 3. The principle of facilitating workpiece clamping; 4. The principle that coarse datum generally cannot be reused. Fine datum: 1. datum Principle of coincidence; 2. 

Principle of unified datum; 3. Principle of mutual datum; 4. Principle of self-basic; 5. Principle of convenient clamping

21. What are the principles for arranging the process sequence?

1. Process the datum surface first, and then process other surfaces; 2. In half of the cases, process the surface first, and then process the holes; 3. Process the main surface 

first, and then process the secondary surface; 4. Arrange the rough machining process first, and then arrange the fine machining process. Processing steps

22. How to divide the processing stages? What are the benefits of dividing processing stages?

Division of processing stages: 1. Rough machining stage·semi-finishing stage·finishing stage·precision finishing stage can ensure sufficient time to eliminate thermal 

deformation and eliminate residual stress caused by rough machining, so as to improve the accuracy of subsequent processing. In addition, when defects in the blank are 

found during the rough machining stage, there is no need to proceed to the next stage of processing to avoid waste. In addition, equipment can also be used rationally, 

low-precision machine tools are used for rough machining, and precision machine tools are dedicated to finishing to maintain the accuracy level of precision machine tools; 

human resources can be reasonably arranged, and high-tech workers specialize in precision and ultra-precision machining, which is important for ensuring Product quality 

and improving process level are both very important.