Constant pressure feed honing
In constant pressure feeding, the feeding mechanism presses against the hole wall with constant pressure, which is divided into three stages.
The first stage is the shedding and cutting stage. This kind of constant pressure honing, due to the roughness of the hole wall at the beginning, the contact area between the oil stone and the hole wall is very small, and the contact pressure is large. Due to the large contact pressure on the surface of the oil stone and the wear of the oil stone binder by the cutting chips, the bonding strength of the abrasive particles and the binder is reduced. Abrasive grains, which means that the whetstone is self-sharpening.
The second stage is the crushing and cutting stage. As honing progresses, the surface of the hole becomes brighter and lighter, the area of contact with the oil stone becomes larger and larger, the contact pressure per unit area decreases, and the cutting efficiency decreases. At the same time, the cutting chips are small and fine, and these chips have little wear on the binder. Therefore, there is very little shedding of whetstone abrasive grains. At this time, the grinding is not by new abrasive grains, but by the tip of the abrasive grains. Therefore, the load on the tip of the abrasive particles is very large, and the abrasive particles are easily broken and broken to form a new cutting edge.
The third stage is the clogging and cutting stage. When honing continues, the contact area between the whetstone and the surface of the hole becomes larger and larger, and extremely fine chips accumulate between the whetstone and the hole wall. Therefore, the cutting ability of whetstone is extremely low, which is equivalent to polishing. If the honing is continued, and the whetstone is seriously clogged to produce a cohesive blockage, the whetstone completely loses its cutting ability and heats up seriously, and the hole accuracy and surface roughness will be affected. At this time, honing should be ended as soon as possible.
Quantitative feed honing
When honing with a fixed amount of feed, the feed mechanism expands the feed at a constant speed to force the abrasive particles to cut into the workpiece. Therefore, there are only shedding cutting and broken cutting in the honing process, and clogging cutting is impossible. This is because when the cutting force generated by the whetstone drops, the feed amount is greater than the actual grinding amount. At this time, the honing pressure increases, which causes the abrasive particles to fall off and break, and the cutting effect is enhanced. When honing by this method, in order to improve hole accuracy and surface roughness, honing without feed can be used for a certain period of time.
Constant pressure-quantitative feed honing
At the beginning, constant pressure feed honing, when the oil stone enters the block cutting stage, it is converted to quantitative feed honing to improve efficiency. Finally, non-feed honing can be used to improve hole accuracy and surface roughness.