The milling machine is a kind of working machine developed after the lathe, and has gradually formed a complete machine tool system. Milling machines have high production efficiency and can process parts of various shapes and certain precision, and are increasingly complete in structure, so they are widely used in machine manufacturing. With the development of new technologies at home and abroad, milling machines are also constantly developing. Due to the wide working range and many types of milling machines, the commonly used milling machines can be divided into four basic types according to their functions, namely, lifting table milling machines, multi-functional milling machines, gantry milling machines, and CNC milling machines.
Universal milling machine, vertical milling machine Milling refers to a cutting method that uses the rotary motion of the milling cutter as the main motion, and the linear or rotary motion of the workpiece or the linear motion of the milling cutter as the feed motion, that is, the workpiece and the milling cutter during milling. The movement is called milling movement and it includes main movement and feed movement.
The main movement is the movement that forms the cutting speed of the machine tool or consumes the main power. In the milling motion, the rotary motion of the milling cutter is the main motion.
The feed movement is the movement required to make the material of the workpiece cutting layer successively put into cutting, thereby machining a complete surface. In the milling movement, the movement or rotation of the workpiece and the movement of the milling cutter are all feed movements. In addition, the feed movement can be divided into three types: longitudinal feed, transverse feed and vertical feed according to the movement direction.
Universal milling machine, vertical milling machine milling amount refers to the amount of cutting used in the milling process, is a parameter to measure the size of the milling movement. The amount of milling includes four elements, namely, milling speed, feed, milling depth and milling width, as shown in Figure 2-45. In the case of ensuring that the workpiece to be processed can obtain the required machining accuracy and surface roughness, the milling speed, feed rate, milling depth and milling width are appropriately selected according to the rigidity and use conditions of the milling machine, tool and fixture.
Milling amount and its calculation
1. Universal milling machine, vertical milling machine milling speed
The linear speed of the main motion is the milling speed, that is, the length of the machined surface traversed by the point on the edge of the milling cutter farthest from the center in 1 minute, expressed by the symbol vc, and the unit is m/min. In actual work, the appropriate milling speed should be selected first, and then the rotation speed should be calculated according to the diameter of the milling cutter.
2. Universal milling machine, vertical milling machine feed
The feed amount refers to the displacement of the tool relative to the workpiece in the direction of the feed movement. According to the needs of the specific situation, there are three representation methods and measurement methods in the milling process.
(1) Feed per tooth fz. When the milling cutter rotates one tooth, the distance the workpiece moves relative to the milling cutter in the direction of feed movement is the feed per tooth, in mm/z.
(2) Feed per revolution f. The distance that the workpiece moves relative to the milling cutter in the direction of the feed movement during one full revolution of the milling cutter is the feed per revolution, and the unit is mm/r.
(3) Feed speed vf. The distance that the workpiece moves relative to the milling cutter in the direction of the feed movement within the time when the milling cutter rotates for 1 min is the feed rate, and the unit is mm/min.
3. Universal milling machine, vertical milling machine milling depth
Milling depth refers to the amount of tool engagement measured in the direction perpendicular to the plane of the workpiece through the base point of the cutting edge, also known as the amount of back engagement, represented by the symbol ap. For milling, the depth of the tool’s penetration into the workpiece, measured along the axis of the milling cutter.
4. Universal milling machine, vertical milling machine milling width
The milling width refers to the amount of cutting tool measured in the direction of feed movement parallel to the workpiece plane and perpendicular to the base point of the cutting edge, also known as the side cutting amount, represented by the symbol ac. For milling, side engagement is the size of the cut part of the workpiece measured perpendicular to the axis of the milling cutter.