9. In order to improve tool life, how should the cutting amount be selected?

Answer: Among the cutting quantities, cutting speed has the greatest impact on tool life, followed by feed rate and cutting depth.

Small. To improve tool life, a reasonable cutting speed should be selected under certain conditions of feed rate and cutting depth.

Spend. Therefore, in order to improve cutting efficiency, we should start by increasing the cutting depth and feed amount, rather than blindly

Increase cutting speed.

10. What are the main causes of crankshaft turning deformation? What measures should be taken to control crankshaft turning deformation?

Answer: The main reasons for crankshaft turning deformation are as follows:

(1) The workpiece is statically unbalanced.

(2) The top or support bolts are too tight.

(3) The top hole is not drilled correctly.

(4) Affected by cutting force and cutting heat.

(5) The accuracy of lathes is low and the cutting speed is improperly selected.

Measures to control crankshaft turning deformation are as follows:

(1) Precisely process the top hole and grind the top hole if necessary.

(2) Carefully correct the static balance of the workpiece.

(3) The top of the center or the top of the supporting bolt must be properly tight. During processing, except for the cutting part, other parts should be firmly supported by the supporting bolt.

(4) Divide the roughing and finishing stages.

(5) Pay attention to adjusting the lathe spindle clearance.

11. What are the methods to reduce the surface roughness of the workpiece?

Answer: Methods to reduce the surface roughness of the workpiece are:

(1) Reduce the residual area height.

(2) Avoid the occurrence of built-up edge.

(3) Eliminate the occurrence of scales and thorns.

(4) Prevent and eliminate vibration marks. .

(5) Avoid wearing bright spots.

(6) Prevent chips from roughening the machined surface of the workpiece.

12. How to cut quenched steel?

Answer: (1) Use cemented carbide with high red hardness and good wear resistance and impact resistance; in the absence of impact load,

Tool materials such as YT30, YT15, YG3 should be used.

(2) Tool angle. Generally speaking, as the hardness of quenched steel increases, the rake angle value of the turning tool should be increased.

The clearance angle for cutting high-hardness steel is no more than 6°.

(3) A turning tool with a smaller tip radius should be used for finishing quenched steel, usually rs≤0.3m.

(4) The cutting amount and cutting speed for turning quenched steel should be higher, and the feed amount and back cutting amount should be smaller.