Device and Method for Broken Tap Removal

Abstract

A device and method for broken tap removal are provided herein. The tap includes a circular longitudinal cavity used for removal and coolant transport. A tap removal tool that is pre-formed to fit the tap's center hole and provides at least three points of contact with the broken tap portion to allow for ease in removing the broken tap.

Claims

1. An internal thread cutting tap: A shaft defining a longitudinal axis: A shaft member comprised of heat-treated or case-hardened steel having a head with engagement flats and shank portion with a distal end, the distal end having an external threaded portion and said threaded portion having at least one longitudinal flute interrupting said threads, and said tap having a circular longitudinal cavity, said circular longitudinal cavity having an internal threaded portion in the externally threaded and fluted end of the tap, said circular longitudinal cavity being a means for coolant transport and removal of a compromised tap.

2. The tap of claim 1 where the circular longitudinal cavity is a through cavity having an opening in said head and an opening in said distal end.

3. The tap of claim 1 where said circular longitudinal cavity is a blind cavity with an opening in said distal external threaded portion and said blind cavity terminating just above said fluted and externally threaded portion.

4. A tap removal tool comprising: A bolt with a head and distal threaded portion and a nut to engage on said threaded portion of the bolt, and said bolt having a longitudinally threaded blind bore in a flat bottom of said threaded portion therein, where said longitudinally threaded blind bore is to accept a threaded rod, and a hollow body is slid over said threaded portion of the bolt and just beneath the nut on said bolt, and said body having a distal end where a lock assembly is encompassed and said body distal end formed with an exterior wrench flats, where said lock assembly accepts an interchangeable flute tab assembly, and said interchangeable flute tab assembly is a hollow longitudinal shaft having at least one flute tab distal said lock assembly portion, and said flute tab is formed to engage in a tap flute, said flute tab retaining a rubber bushing, and said rubber bushing having an opening to accept said flute tab, and where said threaded rod protrudes beyond said distal end of the interchangeable flute tab assembly's said tabs.

5. A method for removing a broken tap providing: An internal thread cutting tap being a shaft member having a head with engagement flats and shank portion with a distal end, the distal end having an external threaded portion and said threaded portion having at least one longitudinal flute interrupting said threads, and said tap having a circular longitudinal cavity, said circular longitudinal cavity having an internal threaded portion in the externally threaded and fluted end of the tap, said circular longitudinal cavity being a means for coolant transport and removal of a compromised tap, and a tap removal tool with a bolt with a head and distal threaded portion and a nut to engage on said threaded portion of the bolt, and said bolt having a longitudinally threaded blind bore in a flat bottom of said threaded portion therein, where said longitudinally threaded blind bore is to accept a threaded rod, and a hollow body is slid over said threaded portion of the bolt and just beneath the nut on said bolt, and said body having a distal end where a lock assembly is encompassed and said body distal end formed with an exterior wrench flats, where said lock assembly accepts an interchangeable flute tab assembly, and said interchangeable flute tab assembly is a hollow longitudinal shaft having at least one flute tab distal said lock assembly portion, and said flute tab is formed to engage in a tap flute, said flute tab retaining a rubber bushing, and said rubber bushing having an opening to accept said flute tab, and where said threaded rod protrudes beyond said distal end of the interchangeable flute tab assembly's said tabs, and where said tap breaks during use in a bore, and said shank portion is removed from said bore, and aforementioned removal tool's bolt head is rotated with a wrench or hand tool of the like, until said threaded rod is seated in the internally threaded portion of the fluted section of said tap, where said body of the removal tool is slid down the bolt until the flute tabs engage in said flutes of the broken tap, and the nut is rotated down to firmly contact the body of said removal tool and said rubber bushing seats on a upper surface of said broken tap, and where a wrench or hand tool of the like is used to engage and rotate said wrench flats of the removal tool body in the opposite direction the tap was rotated to cut threads in the bore, and the broken tap is removed utilizing at least three points of contact between the removal tool and the broken tap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a cross sectional view of the current invention, a tap with a longitudinal cavity used for removal/lubricant transport.

[0008] FIG. 2 is a cross sectional view of the broken tap and removal tool in use.

REFERENCE NUMERALS IN THE DRAWINGS

[0009]

TABLE-US-00001 2 Tap 4 Removal/Coolant Cavity 6 Internal Threaded Tip 10 Bolt 12 Nut 14 Flute Tab 16 Body 18 Rubber Bushing 20 Flute Tab Assembly 22 Broken Tap 24 Threaded Rod 26 Wrench Flats 28 Thread Forming Teeth 30 Lock Assembly 32 Shank 34 Removal Tool

DETAILED DESCRIPTION OF THE INVENTION

[0010] FIG. 1 is a perspective view of the current invention, a conventional tap 2 with a longitudinal removal/coolant cavity 4. Taps 2 are made from metal and undergo a heat-treating process to further strengthen the metal of the tap. It is preferred that the present invention has the removal/coolant cavity 4 incorporated into the tap prior to the heat-treating process but can be machined after the heat-treating process if necessary. The preferred shape of the removal/coolant cavity 4 is round and has an internal threaded tip 6 distal from the wrench flats 26 on the shank 32 therein. In FIG. 1, it can be seen that the removal/coolant cavity 4 runs longitudinally through the center of the tap and may be a through hole or a blind hole beginning at the tip with the thread forming teeth 28 and stop just above the fluted portion of the tap 2. If the tap 2 is compromised and breaks off in a bore during use, the removal tool 34 shown in FIG. 2 is used to remove the broken tap from the hole.

[0011] The removal tool 34, as seen in FIG. 2, is comprised of a bolt 10 with a nut 12, where the bolt 10 has a center hole machined and threaded in the bottom of the bolt 10 to accept a threaded rod 24. After the nut 12 is rotated onto the bolt 10, a hollow body 16 is slid over the bolt until it comes into contact with the nut 12 on the bolt 10. The threaded rod 24 that is rotated into the threaded bore of the bolt 10 protrudes out the bottom of the body 16. The end of the body 16 distal the bolt 10 and nut 12 contains a lock assembly 30 formed to accept an interchangeable flute tab assembly 20 which is made of steel and hollow allowing the threaded rod 24 to protrude out the bottom of the flute tab assembly 20. The portion of the body 16 containing the lock assembly 30 is formed externally to have wrench flats 26. The flute tab assembly 20 end distal the lock assembly 30 point of engagement, has at least one flute tab 14 used to slide into and engage the flute of a broken tap 22. The flute tab 14 is slid through a rubber bushing 18 and is retained by the flute tab 14. Because taps 2 are formed with a varying number of flutes, the removal tool 34 is made to interchange different flute tab assemblies 20 with varying numbers of flute tabs 14.

[0012] The method of removal is herein, in the event a tap 2 is broken off in a bore, the shank 32 portion is removed. The aforementioned removal tool 34 is inserted in the bored hole and remaining piece of broken tap 22, rotated with a wrench or hand tool of the like, on the head of the bolt 10. The threaded rod 24 is rotated into the internal threaded tip 6 of the broken tap 22. Next, the body 16 portion of the removal tool 34, with the correct flute tab assembly 20 is slid down the bolt 10 and into the flutes of the broken tap 22. The nut 12 is then rotated down the bolt 10 until it contacts the body 16 of the removal tool 34 and is sufficiently tightened to the body 16. This forces the rubber bushing 18 to engage the upper surface of the broken tap 22. The removal tool 34 now has at least three points of contact with the broken tap 22. The three points of contact include the threaded rod 24 in the threaded tip 6, the flute tabs 14 seated into the flutes, and the rubber bushing 18 in contact with the top of the broken tap 22. To complete the removal process, a wrench or hand tool of the like is engaged on the wrench flats 26 of the body 16 and rotated in the opposite direction in which the tap was applied to the bore until the broken tap 22 is removed. A new tap 2 can then be rotated into the bore and the thread cutting process can begin again.

[0013] The invention as described hereinabove, with the preferred embodiments, is not to be taken as limited to such, since variations thereof may be made without departing from the spirit and scope of the invention.