Chip Formation

1
Chip Formation??????????????
2
??????????

• ???????? gt Metal cutting gt Machining
• ????????????????????????? (Cutting Tool -Tool)
  ???????????????????????? ???????????????????(?????
  ??????)
• ??????????????????????????????????? Metal Chip
• ??????? ??????? ??????? ???? ????????

3
?????????????? Chip Formation

• ???????????????????????? ??????????????????????
  ? ?????????????????? ?????????????? Ultimate
  Stress - Su

4
Chip
Tool
Shear Zone
2.Friction
1.Shearing
Work pieces
Edge effect
5
?????????????? Chip Formation
?????????????????? Vc
Shear Plane
????????????? ???? tc Deformed Chip Thickness
t ???????????????? Undeformed Chip Thickness
?????????????????? Vw
6
???????????????
?????? Rake angle
???????? Shear Angle
?????? Clearance angle
7
Cutting Process

• ?????????? 3 ??????
• Shearing Process
• Friction Process
• Edge Effect Process

8
Deformation in Cutting

• 1. Primary Deformation ???????????????? ????????
• ??? ?????????????????? ???????????????? Shearing
  ???????????? 1. ??????????????????????
  (???????????????????????? ???? ??????? (Polygon)
  ??????????? ???? ??????
• 2. ?????????? (?x ?x ?) ???????????
  ???????????????????
• 2. Secondary Deformation ?????????????????????????
  ??????????????????? ?????????? (rake face)
  ?????????? Compression ???????????????????????????
  ?????

9
????????????????

• ?? 3 ?????? ???
• ??????????????? Continuous Chip
• ?????????????????? Discontinuous Chip
• ????????????????????????????????? Continuous Chip
  with Built up edge (BUE)

10
????????????????

• Orthogonal Cutting ????????????????
• ????? Cutting edge ????????????????
  ????????????????????????????

11
????????????????

• Oblique Cutting ??????????????
• ????? Cutting edge ???????????????????
  ????????????????????????????
• ???? ??? inclination (?)
• ??? Oblique

12
Shearing in Cutting

• ??????????? ?? 2 ??????
• Thin Shear Zone
• ?????????????? ?????
• Thick Shear Zone
• ????????????? ???????

13
Thin Shear Zone

• rake angle
• Shear angle
• Friction angle
• t Undeformed
• Chip Thickness
• tc Chip Thickness

?
tc
?
?
Tool
t
Workpiece
14
???????? Shear ?

• ???????????? ?????????????????????
  (???????????????????? ????????????????????????????
  ???? Shear
• Continuity Theorem
• ?x tx lx b ? x tc x lc x bc
• b bc (orthogonal)
• t lc
• tc l

Chip length ratio , rl
Chip thickness ratio, rt