With the development of the modern science and technology, all kinds of high and hard materials is used frequently. The traditional cutting technology is difficult to achieve for some higher materials. Coated cemented carbide, ceramics, PCBN, because their higher temperature hardness, wear resistance, thermal and chemical stability, have achieved abvious benefits.
The material of the uperhard materials, the structure of the cutting and their geometric parameters is the basic elements of hard turning. Therefore, how to choose the superhard material tool and how to design the reasonable cutter structure has become very important.
Blade shape and the geometric parameters is very important to tool cutting performance. According to the strength of cutting tool, all kinds of blade shape blade from high to low: circular, 100 ° diamond, square, 80 ° 35 ° 55 °, triangle, diamond, diamond diamond. After the material of the blade is selected, the shape should be choosed as high as possible. The turning blades also should choose as arcradius as possible.
Hardened steel scraps for the red tender, ribbon, brittleness is big, easy to break, not binding. The surface quality of the hardened steel cutting is high. Generally, there is not tumor, but the cutting force is bigger. Especially the radial cutting force is bigger than the main cutting force. The cutting tool should adopt negative rake Angle (go to 5 ° or higher) and the larger Angle (ao = 10 ° ~ 15 °). The main angle depends on machine tool rigidity. Generally under 45° ~ 60°, it can reduce the workpiece and tool chatter.
The higher the workpiece material hardness is, the smaller the cutting speed is. The suitable cutting speed range of superhard cutting tool is 80 ~ 200 m/min, commonly 10 ~ 150 m/min. Adopting large cutting depth, cutting speed should be kept in 80 ~ 100 m/min. In general, cutting deep is between 0.1 ~ 0.3 mm.
Processing the low and rough surface, the optional cutting depth should be appropriate. Between 0.05 ~ 0.25 mm/r, specific value depends on the roughness value of the surface and the requirements of productivity. When the roughness of the surface up to Ra = 0.3 ~ 0.4, using hard turning of superhard cutting tools is economical than the grinding.
In addition to the reasonable choice of the cutting tool, the use of superhard cutting tool in hard turning on a lathe or turning center have not special requirements. When the lathe turning center is enough stiff, the soft workpieces can get the required accuracy and surface roughness. In order to ensure the smooth and continuous turning operation, we commonly adopt rigid clamping device and medium angle cutter. The workpiece in cutting force, under the action of its orientation, bearing and rotating, can keep steady state. And the existing equipment superhard cutting tools can be adopted in hard turning.