Types%20and%20Functions%20of%20Jigs

1
??????????????????????????????
Types and Functions of Jigs
?.?????????? ??????? ????????????????????
??????????????????????????
2
Objectives

• Identify the classes of jigs and fixtures
• Identify the types of jigs and fixtures
• Choose a class and type of jig and fixture for
  selected operations on sample parts

3
Jigs and Fixtures

• The difference between jig and fixture
• Both jigs and fixtures hold, support, and locate
  the workpiece
• The difference is in the way the tool is guided
  to the workpiece.
• A jig guides the cutting tool
• A fixture references the cutting tool

4
Jig and Fixture Design

• Jig A device that holds the work and locates the
  path of the tool.
• Fixture A device fixed to the worktable of a
  machine and locates the work in an exact position
  relative to the cutting tool.

5
Jigs and Fixtures

• The difference between jig and fixture

6
Jigs

• Classes of Jigs
• Jigs may divided into two general classes
• Boring jigs
• used to bore holes or drill in odd size
• Drilling jigs
• used to drill, ream, tap, chamfer, counterbore,
  countersink, reverse spotface, or reverse
  countersink
• The difference is in size of bushing used

7
Jig
??????? ???????? ?????????? ????? ????????????
?????????????
8
Drill Jig
9
Drill Jig
10
Jigs

• Types of Jigs
• Jigs divided into two general types
• Open jigs
• for the parts machined only in one side
• Closed jigs
• used for parts machined on more than one side

11
Channel Jig

• Channel jigs
• Simplest form of box jigs
• Work is held between two sides and machined from
  the third side

12
Jigs Types of Jigs

• Template jigs
• Normally used for accuracy rather than speed
• Fits over the work, not usually clamped
• Least expensive and simplest

13
Template Jig
14
Plate Jig
Similar to template jigs Built-in clamps
15
Table Jig

• Plate jigs
• Sometime made with legs called table jigs

16
Sandwich Jig

• Sandwich jigs
• Form of plate jig with a back plate
• To prevent bending or warping for thin or soft
  parts

17
Angle Jig
Modified Angle Jig

• Angle-plate jigs
• To hold pars that are machined at precise angle
  to their mounting locators

18
Box Jig

• Box jigs
• Usually totally surround the part completely
  machined on every surface

19
Box Jig
20
Box Jig
21
Leaf Gig

• Leaf jigs
• Small box jigs with a hinged leaf to allow for
  easier loading and unloading

22
Leaf Gig
23
Indexing Jig

• Indexing jigs
• Used to accurately space holes around a part
• Reference itself
• Larger indexing jigs are called rotary jigs

24
Diameter Jig
25
Jigs Types of Jigs

• Trunnion jigs
• Form of rotary jig for very large or odd-shaped
  parts

26
Jigs Types of Jigs

• Pump jigs
• Commercially made jigs that must be adapted by
  user
• Very fast load and unload

27
Jigs Types of Jigs

• Multi-station jigs
• Made in any of the forms of jigs
• Commonly used on multiple-spindle machines

28
Drill Jig Components

• Drill bushings
• Precision tools that guide cutting tools such
  as drill and reamers into precise locations in a
  workpiece.

29
Drill Jig Components

• Jig body
• Holds the various parts of a jig assembly.
• Cap screws and dowel pins
• Hold fabricated parts together

30
Drill Jig Components
Screws and Bolt
31
Drill Jig Components

• Locating devices
• Pins, pads, and recesses used to locate the
  workpiece on the jig.

32
Drill Jig Components

• Clamping devices

33
Drill Jig Components

• Locking pins
• Inserted after the first hole is drilled to lock
  or hold the workpiece securely to the jig plate
  while subsequent holes are being drilled.

34
Dimensioning Jig Drawings
35
??????? jig ?????????
36
????????????? Jigs and Fixtures Design Second
Edition, EDWARD G. HOFFMAN