In mechanical parts, the connecting surface plays the role of connection, which is generally relative to a certain plane that has been determined. This topping plane is called the datum plane in machining. When machining the connecting surface, the datum surface should be machined first. Datum machining is a single plane machining.
In addition to the requirements of flatness and surface roughness, the machining of the connecting surface also needs to ensure the position accuracy relative to the datum plane and the dimensional accuracy between the datum plane. Circular milling or end milling is often used to process vertical and parallel surfaces in machining. We have introduced circular milling before. This paper mainly introduces a drooping straight and parallel surface end milling method.
1、 Vertical face milling
1. Use flat tongs to clamp the end and mill the vertical surface
End milling is used to mill the vertical surface of small workpieces. Workpieces are generally clamped with flat tongs, which can be carried out on vertical or horizontal milling machines. When milling with an end milling cutter, the clamping method of the workpiece in the flat tongs, as well as the factors affecting the perpendicularity and the adjustment measures are basically the same as when milling the vertical surface with a circumference.
The difference is: when milling with a cylindrical milling cutter, the cylindricity error of the milling cutter will affect the perpendicularity and parallelism between the machining surface and the datum plane; This is not the case when milling with an end milling cutter, but the perpendicularity error between the spindle axis of the milling machine and the feed direction will affect the perpendicularity and parallelism between the machining surface and the reference surface.
For example, when end milling on the vertical milling machine, if the "zero position" of the vertical milling head is not allowed to use cross feed, a plane inclined to the workbench will be milled; If the longitudinal feed is used for asymmetric milling, an asymmetric concave surface will be milled. Similarly, when end milling on a horizontal milling machine, if the "zero position" of the workbench is not accurate, a slope will be milled with vertical feed; If the longitudinal feed is used for asymmetric milling, an asymmetric concave surface will also be milled.
2. Clamp the end milling vertical surface on the workbench of the horizontal milling machine
It is more accurate and simple to mill the vertical surface with large size on the horizontal milling machine with an end milling cutter. In this way, the milling plane is perpendicular to the worktable. When vertical feeding is adopted, the accuracy is higher because it is not affected by the accuracy of the "zero position" of the workbench.
2、 Parallel face milling
1. End milling parallel surfaces on vertical milling machines
When the workpiece has a step, the workpiece can be directly clamped on the workbench table of the vertical milling machine with a pressing plate, so that the datum plane fits the workbench table.
2. End milling parallel surfaces on horizontal milling machines
When there is no step on the workpiece, the parallel surface can be milled with an end mill on a horizontal milling machine. During clamping, the positioning key can be used for positioning, so that the reference plane is parallel to the longitudinal feed direction. If the bottom surface of the workpiece is perpendicular to the reference plane, no correction is required; If the bottom surface is not perpendicular to the reference plane, it needs to be padded or re milled (so that it is perpendicular to the reference plane). When the leveling method is adopted, a 90 degree angle ruler or dial indicator is needed to correct the datum plane.