遼字石油化工大學⊙ O turning in which the workpiece is rotated and a cutting tool removes a layer of material as the tool moves to the left, as in right Fig. shows OCutting off, in which the cutting tool moves radially inward and separates the right piece from the bulk of the blank SLab milling in which a rotating cutting tool removes a layer of material from the surface of the workpiece CEnd milling, in which a rotating cutter travles along a certain depth in the wo-rkpiece and produces a cavity
● Turuning in which the workpiece is rotated and a cutting tool removes a layer of material as the tool moves to the left,as in right Fig. shows. ●Cutting off,in which the cutting tool moves radially inward and separates the right piece from the bulk of the blank. ●Slab milling,in which a rotating cutting tool removes a layer of material from the surface of the workpiece. ●End milling,in which a rotating cutter travles along a certain depth in the wo-rkpiece and produces a cavity
遼字石油化工大學⊙ In order to analyze this process in detail, a two-dimensional model of it is presented in Fig. 2.2. In this idealized model, a cutting tool moves to the left along the workpiece at a constant elocity, v, and a depth of cut t. a chip is prouced ahead of the tool by plastically deforming and shearing the material continuously along the shear plane This phenomenon can be demonstrated Rough surface Shiny surface by slowly scraping the Rake face Chip Tool surface of a stick of Shear plane Rake anal butter lengthwise with a Flank face sharp knife and Relief or clearance observing the formation Workpiece of a chip Shear angle
In order to analyze this process in detail,a two-dimensional model of it is presented in Fig.2.2.In this idealized model,a cutting tool moves to the left along the workpiece at a constant elocity,v,and a depth of cut t. A chip is prouced ahead of the tool by plastically deforming and shearing the matearial continuously along the shear plane. This phenomenon can be demonstrated by slowly scraping the surface of a stick of butter lengthwise with a s h a r p k n i f e a n d observing the formation of a chip
遼字石油化工大學⊙ B Cutting Factors The factors that influence the cutting process are outlined in Table 2.1 In order to appreciate the contents of this table,lets now identify the major independent variables in the cutting prcess. (atool materials and coatings (b)tool shape, surface finish, and sharpness (c)workpiece material and con-dition (dcutting speed, feed, and depth of cut (e)cutting fluids, (characteristics of the machine tool (g working holding and fixturing
B.Cutting Factors The factors that influence the cutting process are outlined in Table 2.1. In order to appreciate the contents of this table,let’s now identify the major independent variables in the cutting prcess: (a)tool materials and coatings; (b)tool shape,surface finish,and sharpness; (c) workpiece material and con-dition; (d)cutting speed,feed,and depth of cut; (e)cutting fluids; (f )characteristics of the machine tool; (g)working holding and fixturing
遼字石油化工大學⊙ TABLE 2.1 Factors Influencing Machining Operations Parameter Influence and interrelationship Cutting speed, depth of cut Forces, power, temperature rise, tool life, type of chip, feed, cutting fluids surface finish and integrity Tool angles As above; influence on chip flow direction; resistance to tool wear an nd chipping Continuous chir Good surface finish; steady cutting forces; undesirable, especially in automated machinery Built-up edge chip Poor surface finish and integrity; if thin and stable, edge can protect tool surfaces Discontinuous chip Desirable for ease of chip disposal; fluctuating cutting forces: can affect surface finish and cause vibration and chatter Temperature rise Influences tool life, particularly crater wear and dimensional accuracy of workpiece; may cause thermal damage to workpiece surface Tool wear Influences surface finish and integrity, dimensional accuracy, temperature rise, forces and power Machinability Related to tool life, surface finish, forces and pe d type of chip
TABLE 2.1
遼字石油化工大學⊙ Dependent variables in cutting are those that are influenced by changes in the independent variables listed above, and include (a type of chip produced; (b)force and the chip (c temperature rise in the workpiece, the tool, and the chip; (dtool wear and failure (e)surface finishi and surface integrity of the workpiece
Dependent variables in cutting are those that are influenced by changes in the independent variables listed above,and include (a) type of chip produced; (b) force and the chip; (c) temperature rise in the workpiece, the tool, and the chip; (d)tool wear and failure; (e)surface finishi and surface integrity of the workpiece