Locating and Clamping devices in jigs and fixtures.pptx

Locating and Clamping play pivotal roles in any work holding system in Jigs and Fixtures.

1. “ LOCATING AND CLAMPING DEVICES ” Hemant B Patel G. P. VALSAD Department of Mechanical Engineering G. P. VALSAD TOOL ENGINEERING

2. Objectives This lesson will enable the students:- Illustrate the methods of (a) Locating (b) Clamping in fixtures and jigs to facilitate machining.

3. Locating Device The locating device is defined as a device so designed that each successive workpiece when loaded and clamped will occupy the same position in the work holding device. The term locating, as used in language of the tool designer, refers to the dimensional and positional relationship between the workpiece and the cutting tool used on the machine.

4. 3-2-1 principle of location Movements of 12 DOF of Free body in space

5. 3-2-1 principle of location Restricted 9 DOF with 3-2-1 locating principle

6. Types of Locating Devices Locating on Flat surface Solid support locator Adjustable support locator Equalizing locator B. Locating by Holes (Internal surface) By Two pins By a Pin and a Diamond pin By a Pin and Vee locator By Mandrel or plug

7. Continue…. C. Locating on External surface Nesting Locator Ring nesting locator Full nesting locator Partial nesting locator V- Locator Fixed Stop Locator Machined fixed stop locator Installed fixed stop locator Doweled locator Split and Grooved locator

8. Solid Locators

9. Solid Locators Simplest type Easiest and cheapest locator Fixed- height locator Used where machines surface acts as a locating point Mostly used Button locator

10. Adjustable Locators

11. Adjustable Locators

12. Adjustable Locators Variable Height locators Used where surfaces are uneven i.e. Casting and forging Threaded style is the easiest and more economical

13. Equalizer Locator

14. Equalizer Locator They provide equal support through two connected contact points. As one point is pressed, the other lifted and maintains the contact. It especially necessary on uneven cast surfaces.

15. Locating By Holes Locating by two holes as shown in Fig.(a) where one of the pins has to be diamond shaped to accommodate tolerance on the distance between the holes and their diameters. Locating by one hole and an external pin which presents rotation of the blank around the inner pin as shown in fig.(b).

16. Pin locators For locating small diameters of job Pin locators are used.

17. Pin locators

18. Locating by a Pin and V locator

19. Locating by Mandrel or Plug Ring or disc type workpieces are conveniently located on mandrel or single plug

20. Nesting Locator/ Cavity Locator Used to position the work piece. Accurate method for profile location. No need of supplementary locating devices. Commonly there are three types: Ring Nest Full Nest Partial Nest

21. Ring Nest Used for cylindrical W/P. It encloses W/P completely.

22. Full Nest Used for W/P other than Cylindrical. It encloses W/P completely.

23. Partial Nest Used for Larger W/P. It encloses the W/P not Completely.

24. V-block Locator It is generally used to locate cylindrical Job. It can also locate flat jobs having round or angular ends.

25. Adjustable Vee Locator

26. Machined fixed stop Locator Since they are machined into the tool body the entire body has to be changed when locator is worn out.

27. Installed fixed stop locator Most commonly used. Since it is installed into the tool body, So It can be easily replaced when locator is worn out.

28. Doweled locator Dowel pin locator is a fixed locator having maximum use.

29. Split and Grooved locator Split pin or grooved pin type dowel pins are used when tolerances are not too tight for reducing cost and time or production.

30. Fool Proofing

31. Fool Proofing It ensures the parts fits into the tool (Jig/fixture) in its correct position only. Mostly pin is used as fool proofing or fouling pin because it is simplest and cost effective method.

32. Ejecting Devices/Ejectors

33. Ejecting Devices/Ejectors Used to remove the workpiece from close fitted locators and are present behind the workpiece . Speed up the operation by reducing unloading time They are of 2 types: Mechanical Spring plunger

34. Ejecting Devices

35. Clamping Devices Clamping is defind as a device which hold the workpiece against the cutting force acting upon workpiece during maching operation with out causing damage to it. The clamps are also of various types, depending upon shape and dimensions of the job, type of Jig and Fixture and the operation to be performed on the workpiece .

36. Strap Clamp The operation of strap clamp is like a Simple lever.

37. C- washer

38. Screw Clamp This clamp is widely used. The foremost advantages of it are its low cost and simple design. The disadvantage of it is its slow speed of operation .

39. Swing Clamp

40. Hook Clamp

41. Toggle Clamp Horizontal Hold down Toggle clamp

42. Toggle Clamp Vertical Hold down Toggle clamp

43. Toggle Clamp Squeeze Action Toggle clamp

44. Toggle Clamp Straight Line- Action Toggle clamp

45. Toggle Clamp Pull Action Toggle clamp

46. Clamping by Cam Quick clamping by cam is very effective and very simple in operation. Some popular methods and systems of clamping by cam

47. Hook Bolt Clamp It is very simple clamping device. only suitable for light work and where usual tip of the clamp is inconvenient.

48. Bridge Clamp It is very simple and reliable clamping device. The clamping force is applied by spring loaded nut.

49. Heel Clamp These consists of a rusted plate, center stud and heel. The design differ from simple bridge clamp in that a heel is provided at the outer end of the clamp to guide its sliding motion for loading and unloading the work piece.

50. Thank you