Generally, the main angle of the straight edge end mill is fixed, most of them are κ r =75°, and the end mill with a constant value of the main deflection angle κ r , no matter how the back knife is changed during the milling process, the lead angle κ r basically does not change. The leading angle κ r of the circular edge cutter is not the same, and its size changes with the change of the amount of the back knife. Take a 16mm round blade as an example. For example, when the back knife is 4mm, the main angle κ r is 30°, and when the back knife is 2 mm, the lead angle κ r is 20°42′17′′. When the amount of the blade is 1 mm, the main deflection angle κ r is 14° 28′39′′.
(2) Analysis of cutting force of indexable circular edge end mill The cutting force mainly refers to: total cutting force P Z , longitudinal milling component PH, lateral milling component P V and axial milling component P 0 ; The magnitude of the main deflection angle κ r changes, and the relationship between the size and distribution ratio of the three cutting component forces also changes.
According to the technical data, when the main deflection angle κ r is 75°, the milling force of the straight edge milling cutter is theoretically distributed as follows: longitudinal milling force P H = (0.3 ~ 0.4) P Z , lateral milling force PV = (0.85 ~ 0.95) ) P Z , axial milling force P 0 = (0.5 ~ 0.55) P Z .
Through the milling test, the distribution of the milling force of the indexable circular edge end mill is basically: longitudinal milling force PH=(0.33～0.37) P Z , lateral milling force P V =(0.45～0.53) P Z , axial The milling force is P 0 = (0.78 ~ 0.84) P Z (see Figure 2).
Specimen material: ZGMn13, milling cutter diameter = 160 mm, z = 10, γ f = -5 °, λ p = -7 °, insert grade: 767.
Cutting amount: n = 140 r / min, v = 70 m / min, f n = 168 mm / min, f z = 0.12 mm / z.
It can be seen from the above test data that, during cutting, the axial force P 0 increases due to the increase of the blade length of the workpiece which is in contact with the straight edge cutter (the increase of about 40%), and the main deflection angle κ r increases with the back. The change in the amount of the knife changes, and the lateral milling force P V is greatly reduced. The size of the lateral milling force P V is just the main factor affecting the impact of the cutting edge on the workpiece and the wear of the cutting edge. In addition, the thickness of the cutting chip cut by the circular cutting edge is not equal, thus improving the heat dissipation condition. In addition, the cutting zone of the circular arc blade is a circular arc shape without a blade edge without corners, and there is no weak zone, which causes the mechanical impact and thermal shock to be suffered during the cutting process to be small, so the tool life of the arc blade will be Greatly improve.
Economic life of cutting parameters when selecting <br> <br> 4. The milling cutting parameters should be processed according to the workpiece material, and the binding machine power, and the rigidity of the tool fixture into account, in order to obtain the best economic effect.
The processing precision of high manganese steel frogs is not very high, and it is rough processing. During the cutting process, due to the influence of plastic deformation and cutting force, severe hardening occurs in the cutting layer and a certain depth below the surface. In order to avoid the hardened layer caused by the surface of the blank and the previous pass, a larger amount of backing and feed was selected during the cutting process. Compared to straight edge end mills, when using a circular edge end mill, the cutting speed is reduced.
High-manganese steel frogs are machined with a circular-arc end mill. Generally, the amount of the back-feeding knife is a p = 3-5 mm, the feed rate is f z = 0.1-0.15 mm/z, and the cutting speed is taken as v=60-80 m/ Min. After production practice, the comprehensive effect is good.
5. Conclusion <br> <br> arcuate edge end mill carbide simple structure, less attachment, easy clamping, high precision, high manganese steel frog for processing, can effectively overcome the strength of the straight edge of the end mill Low, worn, and severely chipped. Compared with the square blade, the circular blade can be indexed 2 to 3 times, making full use of the tool material, thereby reducing production costs. Practice has proved that the use of carbide arc-edge milling cutters for high-manganese steel frogs is feasible.
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