Plug removal method and apparatus

• US 8,307,529 B2
• Filed: 01/05/2010
• Issued: 11/13/2012
• Est. Priority Date: 01/05/2010
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Chapin, Curtis M., Schueler, John T.
• Primary Examiner(s): Hong, John C
• Application Number:
  US12/652,354
• Publication Number:
  US 20110162186A1
• Time in Patent Office: 1,043 Days
• Field of Search: 294/261, 294/265, 294/266, 297/00, 292/78, 292/80, 292/70, 254/18, 227/63, 81/532
• US Class Current: 29/426.5
• CPC Class Codes: B25B 27/02 for connecting objects by press fit or detaching same B25D1/16 takes precedence
• CPC Class Codes: B25B 27/04 inserting or withdrawing keys
• CPC Class Codes: Y10T 29/49822 by applying force
• CPC Class Codes: Y10T 29/53909 Means comprising hand manipulatable tool

Abstract

A tool for removing plugs from recesses obviates the need for a twist of the wrist in engaging a plug for removal. A plunger is carried by a housing and is supported for reciprocal axial motion between extended and retracted positions relative to the housing. A shaft of the plunger includes a first threaded section that is engaged in a nut carried by the housing and has threads pitched to allow relative axial motion to be converted to relative rotation between shaft and housing. A second threaded section of the plunger shaft is configured to tap into a plug in response to shaft rotation in a tapping direction, and has a shallower thread pitch than the first threaded section.

Claims

1. An apparatus for removing plugs from recesses, the apparatus comprising:

a housing;

a nut carried by the housing; and

a plunger carried by the housing and supported for reciprocal axial motion between extended and retracted positions relative to the housing, the plunger including a plunger shaft having;

a first threaded section threadedly engaged in the nut and including threads pitched to convert relative axial motion to relative rotation between the plunger shaft and the housing; and

a second threaded section at a forward end of the plunger shaft, the second threaded section being configured to tap into a plug comprising softer material in response to shaft rotation in a tapping direction;

the second threaded section of the plunger shaft having a shallower thread pitch than the first threaded section.

2. An apparatus as defined in claim 1 in which the handedness of the second threaded section of the plunger shaft is opposite that of the first threaded section.

3. An apparatus as defined in claim 1 in which the plunger is axially biased toward the retracted position.

4. An apparatus as defined in claim 1 in which the plunger includes a plunger head connected to an aft end of the plunger shaft in a manner that allows for plunger shaft rotation relative to the plunger head.

5. An apparatus as defined in claim 1 in which the second threaded section:

protrudes from a forward end of the housing when the plunger is in its extended position; and

is withdrawn into the housing when the plunger is in its retracted position.

6. An apparatus as defined in claim 1 in which finger tabs extend laterally from an aft end of the housing.

7. An apparatus as defined in claim 1 in which the second threaded section comprises threads that taper to a point.

8. An apparatus as defined in claim 1 in which the housing includes a plug hopper configured to store plugs.

9. An apparatus as defined in claim 8 in which a magnetic strip is carried by the plug hopper in a position to retain plugs comprising a ferrous filler.

10. An apparatus as defined in claim 8 further including a lamp carried by the plug hopper and positioned to direct a beam of light generally toward a position where the second threaded section is located when the plunger shaft is in its extended position.

11. An apparatus as defined in claim 10 in which a forward wall of the plug hopper carries the lamp, the forward end of the plug hopper being ramped so as to carry the lamp in a position displaced axially aft of a forward end of the housing.

12. An apparatus as defined in claim 1 in which a forward end of the housing includes a recess disposed coaxially with the plunger shaft and a plunger shaft opening and is configured and positioned to receive a removed plug as the plunger shaft is retracted into the housing through the plunger shaft opening, and is further configured to retain the plug.

13. An apparatus as defined in claim 12 further including a plug receptacle carried by the housing and including flaps positioned to flex to allow passage of a retracting fastener plug into the plug receptacle and to then return to respective closed positions to prevent the plug from dropping out of the plug receptacle after being stripped from the second threaded section of the plunger shaft.

14. An apparatus as defined in claim 1 in which the thread pitch of the first threaded section of the plunger shaft is in the range of approximately 2.5 to 8.5 mm.

15. An apparatus as defined in claim 1 in which the thread pitch of the first threaded section of the plunger shaft is approximately 5 mm.

16. An apparatus as defined in claim 1 in which the thread pitch of the second threaded section of the plunger shaft is in the range of approximately 0.6 to 2.5 mm.

17. An apparatus as defined in claim 1 in which the thread pitch of the second threaded section of the plunger shaft is approximately 0.8 mm.

18. A method for removing plugs from recesses, the method including the steps of:

providing an apparatus comprising a plunger supported in a housing for reciprocal motion between extended and retracted positions relative to the housing and including a plunger shaft having a first threaded section threadedly engaged in a nut carried by the housing, the first threaded section including threads pitched steeply enough to allow relative axial motion to be converted to rotational shaft motion relative to the housing, and a second threaded section at a forward end of the plunger shaft and configured to tap into a softer material, the second threaded section of the plunger shaft including threads pitched less steeply than the threads of the first threaded section and sufficiently shallow to frictionally prevent relative rotation in response to relative axial motion;

extending the second threaded section of the plunger shaft from the housing by moving the plunger shaft toward its extended position;

engaging a forward tip of the second threaded section of the plunger shaft against the plug;

tapping the second threaded section into the plug by pressing the tip of the second threaded section against the plug and moving the housing axially relative to the plunger such that the plunger shaft is driven in rotation relative to the housing in a tapping direction; and

withdrawing the plug by pulling the device aft with the second threaded section carrying the plug.

19. The method of claim 18 in which:

the step of providing an apparatus includes providing a plunger shaft having first and second threaded sections, which are threaded in opposite directions;

the step of providing an apparatus further includes providing a spring positioned to bias the plunger toward the retracted position; and

the step of tapping the second threaded section includes allowing a spring bias to move the housing axially forward relative to plunger such that the plunger shaft is driven in rotation relative to the housing in the tapping direction.

20. The method of claim 19 including the additional step of stripping an extracted plug from the second threaded section by allowing the spring bias to draw the second threaded section back into a retracted position within the housing.