Honing tube honing process principle

Honing tube honing process principle

Honing is a special form of grinding and an efficient machining method in finishing. This process not only removes large machining allowances (honing or polishing in the 1950s), but also is an effective machining method to improve part size, geometric accuracy and surface roughness.

(I) Characteristics of Honing:

High processing accuracy: Especially for some small and medium-sized optical through holes, the cylindricality can reach within 0.001mm. Some parts with uneven wall thickness, such as connecting rods, can achieve a roundness of 0.002mm. For large holes (bore diameters within 200mm), the roundness can reach 0.005mm. If there are no annular grooves or radial holes, etc., straightness is also possible within 0.01mm. Honing is more accurate than grinding. When grinding, the bearing supporting the wheel is outside the honing hole, which will cause deviations, especially for small holes. Grinding is worse than honing accuracy. Honing can generally only improve the accuracy of the shape of the workpiece. To improve the position accuracy of the part, some necessary measures need to be taken. For example, use a panel to improve the perpendicularity between the end surface of the part and the axis (the panel is installed on the stroke arm, adjust it to be perpendicular to the rotating spindle, and the part can be processed on the panel).

Good surface quality: the surface is cross-textured, which is conducive to the storage of lubricant and the maintenance of oil film. Has a high surface support ratio (the ratio of the actual contact area between the hole and the shaft to the fit area between the two), so it can withstand larger loads and wear resistance, thereby improving the service life of the product. The honing speed is low (a few tenths of the grinding speed), and the oil stone is in surface contact with the hole, so the uniform grinding pressure of each abrasive particle is small, so the heat generation of the workpiece is very small, and the workpiece surface is almost free of thermal damage And the metamorphic layer, the deformation is small. The honing machined surface is almost free of embedded sand and extruded hard layers. Grinding has a higher cutting pressure than honing. The grinding tool and the workpiece are in line contact and have a relatively high speed. As a result, high temperatures can be generated in local areas, which can cause permanent damage to the surface structure of the part.

Wide processing range: mainly processing various cylindrical holes: light through holes. There are interrupted holes in the axial and radial directions, such as radial or slot holes, key slot holes, and spline holes. Blind hole. Multi-step holes and so on. In addition, with a dedicated honing head, it is also possible to process conical holes, oval holes, etc., but the honing head has a complicated structure and is generally not used. Cylindrical bodies can be honing with a cylindrical honing tool, but the margin for removal is much smaller than the cylindrical honing margin. It can process almost any material, especially diamond and cubic boron nitride abrasive applications. It also improves the efficiency of honing.

(II) Honing processing principle:

Honing is the use of one or more oil stones installed on the circumference of the honing head. The oil stone is expanded radially by an expansion mechanism (both rotary and push-type), so that it is pressed against the hole wall of the workpiece to produce a certain Surface contact. At the same time, the honing head is rotated and reciprocated without moving the parts; or the honing head is only rotated and the workpiece is reciprocated to achieve honing.

In most cases, the honing head is floating between the machine tool spindle or the honing head and the workpiece holder. 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, and the formation of the hole surface basically has the characteristics of the creation process. The so-called creation process is that the whetstone and the hole wall face each other and are trimmed to form the hole wall and the surface of the whetstone. Its principle is similar to the principle of two plane-moving plates facing each other to form a plane. During honing, the honing head rotates and reciprocates, or the honing head rotates the workpiece to and fro, so that the machining surface forms a cross spiral cutting trajectory, and the number of revolutions of the honing head is not an integer during each reciprocating stroke time. The head is staggered at a certain angle relative to the workpiece in the circumferential direction, so that the movement of each abrasive particle on the honing head on the hole wall will not repeat. In addition, with each turn of the honing head, the cutting track of the whetstone and the previous turn has an overlapping length in the axial direction, so that the connection of the front and back grinding tracks is smoother and more uniform. In this way, during the entire honing process, the chances of each point of the hole wall and the stone surface interfering with each other are almost equal. Therefore, as the honing progresses, the hole surface and the surface of the oil stone continue to produce interference points. These interference points are continuously ground to produce new and more interference points, and they are continuously ground, so that the contact area between the surface of the hole and the stone is increasing. The degree of interference and cutting effect continue to weaken, and the roundness and cylindricity of the hole and the whetstone continue to improve. Finally, the process of creating the hole surface is completed. In order to obtain better cylindricity, where possible, parts are often turned around in honing, or the mutual position of the honing head and the workpiece in the axial direction is changed. One point to be noted: Because the honing oil stone uses diamond and cubic boron nitride abrasives, the oil stone wear is very small during processing, that is, the amount of oil stone affected by the workpiece is very small. Therefore, the accuracy of the hole depends to some extent on the original accuracy of the oilstone on the honing head. So when we use diamond and cubic boron nitride whetstone, we need to trim the whetstone well before honing to ensure the accuracy of the hole.