Техническая информация Sumitomo - страница 2

Предыдущая страница Следующая страница

Навигация

Technical Guidance Basics of Turning Turning Edition ■ Calculating Cutting Speed ■ Calculating Power Requirement (1) Calculating rotation speed from cutting speed f n : Spindle speed (min-1) Pc : Net power requirement (KW) 1,000 × vc vc : Cutting speed (m/min) øDm n n= π × Dm Dm : Diameter of work piece (mm) vc × f × a p × k c vc : Cutting speed (m/min) π : ≈ 3.14 ap Pc = 60 × 103 × η f : Feed rate (mm/rev) ap : Depth of cut (mm) (Ex.) vc=150m/min, Dm=100mm Pc kc : Specific cutting force (MPa) 1,000 × 150 Feed Direction H= 0.75 H : Required horsepower (HP) n= 3.14 × 100 = 478 (min -1) η : Machine efficiency · n : Spindle speed (min-1) (0.70 to 0.85) (2) Calculating cutting speed from rotational speed · vc : Cutting speed (m/min) ● RoughValue of kc · f : Feed rate (mm/rev) vc = π × Dm × n Refer to the above table · ap : Depth of cut (mm) Aluminium: 800MPa 1,000 · Dm : Diameter of work piece (mm) General Steel: 2,500 to 3,000MPa Cast Iron: 1,500MPa ■ Cutting Force ■ Relation Between Cutting Speed and Cutting Force ■ Relation Between Feed Rate and Specific Cutting Force (For Carbon Steel) (N) 1,600 Rake angle: -10° 8,000 Force Traverse Rupture Strength Ff 800MPa Principal 800 600MPa Rake angle: 0° (MPa) 6,000 400MPa Fp 00 80 160 240 Fc: Principal force Cutting Speed (m/min) Force Ff : Feed force Fc Fp: Back force ■ Relation Between Rake Angle and Cutting Force Cutting 4,000 ● Calculating Cutting Force Force (N) 2,800 Specific P : Cutting force (kN) 2,400 P= kc × q kc : Specific cutting force (MPa) 2,000 1,000 q : Chip area (mm2) Principal 2,000 = kc × ap × f ap : Depth of Cut (mm) 1,600 1,000 f : Feed Rate (mm/rev) 20 10 0 −10 −20 Rake Angle (Degree) 0 0.1 0.2 0.4 0.04 Feed Rate (mm/rev) When feed rate decreases, specific cutting force increases. ■ Machined Surface Roughness ■ Relation Between Nose Radius and Cutting Force ● Theoretical Surface Finish ● Ways to Improve Machined Surface Roughness 4000 (N) 3500 Principal h : Theoretical surface roughness (mm) (1) Use an insert with a larger nose radius. force h= f2 × 103 f : Feed rate (mm/rev) (2) Optimise the cutting speed and feed rate Force 8 × RE RE : Nose radius (mm) so that built-up edge does not occur. Feed force Cutting 1500 h (3) Select an appropriate insert grade. 1000 f (4) Use wiper insert Back force RE 500 0.4 0.8 1.2 1.6 Nose Radius (mm) Large nose radius ● Actual Surface Roughness increases back force. N Steel: Work : SCM440(38HS) Theoretical surface finish x 1.5 to 3 Inserts : TNGA2204 SS Technical Guidance / Cast iron: Holder : PTGNR2525-43 References Theoretical surface finish x 3 to 5 Cutting Conditions : vc=100m/min ap=4mm f =0.45mm/rev N10