Selection of cutting parameter

Cutting speed, feed and cutting depth is called cutting parameter. They are the important factors influencing the workpiece processing quality and production efficiency. Turning, maximum diameter workpiece machining surface of the linear velocity is called cutting speed, v ( m/min) Said. Its computation formula: v = PI dn / 1000 ( m/min) Type: d - — The diameter of the workpiece for machining surface ( mm） n— — Lathe spindle speed (per minute r / min) Every week, tool by moving distance, known as feed to f ( mm/r) Said. Tool each time slice to the thickness of the metal layer, called the cutting depth, the ap ( mm) Said. In order to guarantee the machining quality and productivity, in every stage of parts machining, medium precision parts, general according to coarse car a fine solution. Coarse car as soon as possible from the blank is the purpose of the cut off most of the machining allowance, close to the required shape and size of components. Coarse car give priority to in order to improve the productivity, increase the cutting depth in the production, to improve the productivity in the most favourable, followed by appropriate increase feed, and adopts medium or medium to low cutting speed. Using high speed steel lathe tool for rough turning cutting dosage recommendations are as follows: cutting depth ap = 0. 8 to 1. 5 mm, feeding f = 0. 2 to 0. 3 mm/r, cutting speed v take 30 ~ 50 m/min ( Cutting steel) 。 Rough casting, forging blank, because of the workpiece surface is hard cover, to protect the tip, should first surfacing or chamfering, cutting depth should be greater than the first time, a hard skin thickness. If the length of the workpiece clamping is shorter or surface convex gravamen, cutting dosage shoulds not be too large. Coarse car zero shall be maintained. 5 ~ 1 mm as a fine car allowance. Coarse accuracy is IT14 - after the car Normally for 12 IT11, surface roughness Ra value. 5 ~ 6. 3μm。 Fine car is to ensure that the purpose of parts size accuracy and surface roughness requirements, should as far as possible under the premise improve productivity. Generally finish turning precision of IT8 ~ IT7, surface roughness Ra = 3. 2 to 0. 8 microns, so fine car is give priority to in order to improve the machining quality of workpiece. Cutting dosage should choose small cutting depth ap = 0. 1 to 0. 3 mm and smaller feeding f = 0. 05 ~ 0. 2 mm/r, cutting speed. Fine car another outstanding issue is to ensure that the processing surface roughness requirements. Cut on surface roughness Ra value of main measures are as follows. ( 1) Reasonable selection of cutting dosage. Choose smaller cutting depth and feed ap f, can reduce the residual area, reduce Ra value. ( 2) Appropriate decrease deputy Angle Kr ', or have small arc blade grinding, to reduce the residual area, reduce Ra value. ( 3) The Angle between 0 before proper enlargement, the grinding more sharp edge. ( 4) Fuel oil after grinding tool surface before and after the knife, the Ra value to 0. 2 to 0. 1 microns, which can effectively reduce the Ra value of the workpiece surface. ( 5) The rational use of cutting fluid, can also help reduce the machining surface roughness Ra value. Low speed fine car use emulsion or oil; If cast iron with low speed fine vehicles use kerosene, high-speed precision car steel and high speed cutting precision cast iron parts, car generally does not use cutting fluid.