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High Efficient Turning
What is CNC turning?
The workpiece rotates, and the turning tool performs linear or curved movement cutting in the plane. Turning is generally carried out on a lathe to machine internal and external round turnings of workpieces. Turning cylindrical surfaces, end surfaces, conical surfaces, forming surfaces, and threads.
When turning the inner and outer cylindrical surfaces, the turning tool moves in a direction parallel to the axis of rotation of the workpiece. When turning an end face or cutting a workpiece, the turning tool moves horizontally in a direction perpendicular to the axis of rotation of the workpiece. If the trajectory of the turning tool is at an oblique angle to the axis of rotation of the workpiece, the conical surface can be machined. Turning formed rotary surfaces can use the forming tool method or tool tip trajectory method. During turning, the workpiece is rotated by the spindle of the machine tool to act as a master; the turning tool held on the tool holder is used for the feed motion. Cutting speed v is the linear speed (m/min) at the contact point between the rotating workpiece and the lathe. The cutting depth is the vertical distance (in millimeters) between the workpiece surface and the machined surface at each cutting stroke. Cutting and forming turning are the length of contact (in millimeters) between the turning tool and the workpiece perpendicular to the feed direction. The feed amount indicates the amount of displacement (mm/rev) in the feed direction of the turning tool when the workpiece rotates one revolution, and it can also be expressed in terms of the feed per minute of the turning tool (mm/min). With high-speed steel lathe turning ordinary steel, the cutting speed is generally 25 ~ 60 m / min, cemented carbide turning tool up to 80 ~ 200 m / min; with coated carbide turning tool, the maximum cutting speed of up to 300 Meters/minute or more.
Turning is generally divided into rough and fine cars (including semi-finish cars). The roughing vehicle strives to improve the turning efficiency without reducing the shear speed, using a large depth of cut and a large feed rate, but the machining accuracy can only reach IT11, and the surface roughness is Rα20 to 10 μm; semi-finishing and finish turning Use high speed and small feed and cutting depth as much as possible. The machining accuracy can reach IT10 ~ 7, and the surface roughness is Rα10 ~ 0.16 μm. The high-precision precision turning non-ferrous metal parts used on high-precision lathes can achieve machining accuracy of IT7 to 5 and a surface roughness of Rα0.04 to 0.01 μm. This turning is called “mirror turning.” If a concave or convex shape of 0.1 to 0.2 μm is machined on the cutting edge of a diamond turning tool, the surface of the turning will have a very fine pattern of irregularities and stripes, which will give a satin-like luster under the diffraction of light. As a decorative surface, this turning is called “shiny turning.”
During turning, if the turning tool is rotated at the same time, the turning tool is rotated in the same direction as the workpiece with the corresponding rotation speed (the tool rotation speed is generally several times of the workpiece rotation speed), and the relative movement of the turning tool and the workpiece can be changed and processed. Workpieces with polygons (triangles, squares, prisms, hexagons, etc.). If the tool is longitudinally fed, a periodic radial reciprocating motion is imparted to the tool holder relative to each revolution of the workpiece, and the surface of the cam or other non-circular cross section can be machined. On a tooth turning lathe, the flank face of some multi-tooth tools (such as a form cutter and a gear hob) can be machined according to the similar working principle, which is called “shovel back”.