In order to ensure that a sufficiently high average chip thickness per tooth feed is used, the number of cutter teeth suitable for this process must be correctly determined. The pitch of the milling cutter is the distance between the effective cutting edges. According to this value, the milling cutter can be divided into three types - a fine-tooth milling cutter, a sparse-tooth milling cutter, and a special-tooth milling cutter.
Also related to the chip thickness of the milling is the leading angle of the face milling cutter. The lead angle is the angle between the main cutting edge of the insert and the surface of the workpiece, with a 45 degree, 90 degree angle and a circular insert. The change of the cutting force direction will change greatly with the difference of the main declination: the milling cutter with the main declination of 90 degrees mainly produces radial force, which acts in the feed direction, which means that the surface to be machined will not be subjected to More pressure is more reliable for workpieces with weaker milling structures.
The milling cutter with a main angle of 45 degrees has roughly the same radial cutting force and axial direction, so the pressure generated is relatively balanced and the machine power requirements are relatively low. It is especially suitable for milling short-cut materials that produce chipping chips. Workpiece.
A circular blade milling cutter means that the main deflection angle varies continuously from 0 to 90 degrees, depending on the depth of cut. This blade has a very high cutting edge strength and is suitable for large feed rates due to the relatively thin chips generated along the long cutting edge. The direction of the cutting force along the radial direction of the insert is constantly changing and the pressure generated during machining will depend on the depth of cut. The development of the geometric geometry of the modern blade makes the circular blade have the advantages of smooth cutting effect, low power requirement for the machine tool and good stability. Today, it is no longer an effective roughing cutter, and it has a wide range of applications in face milling and end milling.
There are two ways to feed the workpiece and the direction of rotation of the milling cutter. The first is down-cutting. The direction of rotation of the milling cutter is the same as the direction of feed of the cutting. At the beginning of the cutting, the milling cutter bites the workpiece and cuts the last chip. The second type is up-cut milling. The direction of rotation of the milling cutter is opposite to the direction of feed of the cutting. The milling cutter must slide over the workpiece before starting the cutting. The cutting thickness starts at zero and the cutting thickness reaches the end of the cutting. maximum.
When three-sided milling cutters, some end milling or face milling, the cutting forces have different directions. In face milling, the milling cutter is just outside the workpiece, and the direction of the cutting force should be especially noted. When milling, the cutting force presses the workpiece against the table, and the cutting force causes the workpiece to leave the table during up-cut milling.
Since the cutting effect of the down-milling is the best, the down-cutting is usually preferred. Only when the machine has a thread gap problem or if there is a problem that cannot be solved by the down-milling, the up-cutting is considered.
Ideally, the cutter diameter should be larger than the width of the workpiece, and the cutter axis should always be slightly off the workpiece centerline. When the tool is placed against the center of the cutting, burrs are easily generated. The direction of the radial cutting force as the cutting edge enters the cutting and exits the cutting will continue to change. The machine tool spindle may vibrate and be damaged, the blade may break and the machined surface will be rough. The milling cutter is slightly off center and the cutting force direction will no longer fluctuate - the milling cutter will get a preload. We can drive the center milling to the center of the road.
Each time the milling insert enters the cutting, the cutting edge is subjected to an impact load, which depends on the cross-section of the chip, the material of the workpiece and the type of cutting. It is an important direction for proper bite between the cutting edge and the workpiece when cutting in and out.
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