Honing machining principle
Honing is the use of one or more whetstones installed on the circumference of the honing head, and the whetstones are expanded in the radial direction by the expansion mechanism (both rotary and propulsion) to press against the workpiece hole wall in order to produce Face contact. At the same time, the honing head is rotated and reciprocated, and the parts are not moved; or the honing head only performs rotary motion, and the workpiece reciprocates, thereby achieving honing.
In most cases, the honing head and the machine tool spindle or between the honing head and the workpiece fixture are floating. In this way, the honing head is guided by the hole wall of the workpiece during processing. Therefore, the machining accuracy is less affected by the accuracy of the machine tool itself, and the formation of the hole surface basically has the characteristics of the creation process. The so-called creation process is that the oil stone and the hole wall are researched against each other and trimmed to form the hole wall and the oil stone surface. The principle is similar to the principle that two plane-moving plates face each other to form a plane.
During honing, the honing head rotates and reciprocates or the honing head rotates the workpiece to reciprocate, so that the processing surface forms a cross-helical cutting track, and the number of revolutions of the honing head is not an integer during each reciprocating stroke time, so between two strokes, honing The head is shifted by a certain angle with respect to the workpiece in the circumferential direction. Such a movement makes the movement trajectory of each abrasive grain on the wall of the honing head not repeat. In addition, for each revolution of the honing head, the cutting trajectory of the whetstone and the previous revolution have an overlapping length in the axial direction, making the connection of the front and rear grinding trajectories smoother and more uniform. In this way, during the honing process, the chances of each point of the hole wall and the oilstone surface interfering with each other are almost equal. Therefore, as honing progresses, interference points continue to be generated on the surface of the hole and the surface of the whetstone. These interference points are constantly removed and new and more interference points are generated. The degree of interference and the cutting effect continue to weaken, and the roundness and cylindricity of the hole and whetstone also continue to increase, and finally the creation process of the hole surface is completed. In order to obtain better cylindricity, when possible, the part is often turned around during honing, or the mutual position of the honing head and the workpiece axis is changed.
It should be noted that since the honing whetstone uses abrasives such as diamond and cubic boron nitride, the whetstone wears little during processing, that is, the whetstone is trimmed by the workpiece. Therefore, the accuracy of the hole depends to some extent on the original accuracy of the whetstone on the honing head. Therefore, when using diamond and cubic boron nitride whetstone, the whetstone should be trimmed well before honing to ensure the accuracy of the hole.