Tham khảo tài liệu 'process planning episode 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Process parameters 235 where T is the machining time min D the diameter of the workpiece mm A an allowance for tool approach and exit mm r the feed rate mmrev-1 and N the revolutions of the cutter for milling drilling or the workpiece for turning and boring in rev min-1. It should be noted that rjV in the equation is actually equal to m as stated in Section . The application of these is best illustrated through a worked example. Example Consider the component in Example Fig. once again. The component is to be made from mild steel with carbide tooling at a constant surface speed of lOOmmhr1 on a lathe with a maximum spindle speed of 1500 rev min 1. The machining allowance is 2mm. Determine i if the lathe is capable of turning the component at the required surface speed ii the total machining time for the component if the lathe is capable. Solution i 1. Facing 050mm _ _ d- d D D 2 2 3 i 50mm 50 0 d2 0mm D - 2 25 mm . - 1000K vc lOOmmin-1 N c c ttD Z 25mm 1000 X 100 _ __. -1 N N ---- rev min 77 X 25 2. Turning 0 50mm . -1 1000K vc lOOmmin-1 N c ttD D 50mm . Ố 7 _ 1000 X 100 _ .__. -1 N N ---- rev min 77 X 50 3. Turning taper d 4 d2 D D 2 2 ựi 50mm 50 75 d2 75 mm D ---------T mm 236 Process Planning . . 1OOOVC vc lOOmmin-1 N -_lr ttD D 1000 X 100 _ nQ . N N ----. rev min TT X 4. Turning 0 75 mm . 1OOOVC vc lOOmmin 1 N 2-1- c ttD D 75mm 1000 100 N N ---- rev min 7T X 75 5. Parting off __ dỵ 4 di D D - 2 2 4 75mm 75 0 di 0mm D - mm z 2 . . 1000K Vc lOOm min N c ttD mm _ 1000 X 100 _ o o I N N ---- z rev min TT X According to the above spindle speed calculations the lathe is capable of machining the component at the required surface speed. ii From Table the feed rateyr to be used is . 1. Facing 050mm . . 0 2 A Z 50mm 50 2 2 n . A 2mm T 0 80x 1273 24 -027 min fr N 2. Turn 050mm rji_ rrt _ L T A 7ĨT The actual diameter is used as .
