EASY-OUT THREADED FASTENER EXTRACTOR

Abstract: An easy-out threaded fastener extractor combination tool wherein an extractor (20) is combined with a drill head (12) so that in use the drilling and extracting opera­ tion is performed at the same time. The extractor (20) is threadably mounted on the drill bit shaft (14) and moveable along the longitudinal axis thereof enabling the drill bit (12) to penetrate within a broken bolt and subsequently having the extractor (20) engaging the same for removal. A suitable drive head (16) is provi­ ded for a drill chuck or other force producing device.

Description: The present invention relates to a tool assembly for extracting a broken threaded fastener having the features of the first part of claim 1 (see for example US-A-2752671). Other conventional easy out type bolt extractors for extracting broken bolts within a threaded bore are formed with gripping teeth and/or shaped flutes adapted to engage the sides of a previously drilled bore through the broken bolt. The gripping surfaces remove the threaded bolt when the extractor is rotated in a direction opposite to that of the bolt threads. These extractors require that the hole be drilled first through the broken bolt prior to the insertion of the extractor. A shortcoming of this tool is that the drill bit is often broken in the process of drilling which results in a compound problem of removal of both the broken bolt and the broken drill bit. Even when the drill bit is not broken, the bolt is often driven deeper into the threaded hole making extracting more difficult. This process requires that the drill bit be removed before inserting the bolt extractor so that at least three separate operations are needed. Among the objects of the present invention are the provision of a threaded fastener extractor tool which is combined with a drilling bit so that a broken bolt may be removed in a single operation. The invention is defined in claim 1 As with the easy-out threaded fastener extractor of the previous invention, the present invention combines the drill bit and bolt extractor in a single tool. The lower surface of the tool is provided with the drill bit having a cutting edge with a pitch in the direction opposite to the threads of the bolt bore. A bolt extractor is threadedly mounted on the drill bit shaft above the drill bit. The top of the tool includes a drive head which is adapted to coact with a power or hand drill or other suitable driving means. Figure 1 is an elevational view of the bolt extractor combination tool according to the present invention. Figure 2 is a sectional view taken along the lines 2-2 of figure 1. Figure 3 is a sectional view taken along the lines 3-3 of figure 1. Figure 4 is a sectional view taken along the lines 4-4 of figure 1. In the drawings, the easy-out type of bolt extractor tool 10 of the present invention is shown including a drill bit 12 mounted on a threaded shaft 14. The opposite end is formed with an integral drive head 16 adapted to be provided with a suitable driving force such as a power drill chuck or hand-driven wrench. Assuming most broken bolts which are to be removed have right-handed threads, the drill bit 10 will be of the left-hand type. An extractor 20 is formed with a central bore and includes tapered fluted teeth 22 which are adapted to grip an interior bore surface when rotated in a left-hand thread or counterclockwise direction, assuming the bolt to be extracted has right-hand threads. The teeth 22 are separated by longitudinal slots which provide increased resiliency when gripping the interior bore of a broken threaded bolt. The extractor includes interior threads and is reciprocally and rotatably moveable along the longitudinal axis of the threaded shaft 14. With the aforementioned structure, driving the compound tool into a broken bolt by a suitable drive means forms a bore. It will be appreciated that various changes and modifications may be made to the above-described invention, whose definition is given in claim 1.

Claims: A tool assembly for extracting a broken threaded fastener threaded in a first direction of tightening in a bore, the assembly comprising: drill means (12) for forming a bore in the broken fastener upon rotation in a second direction opposite to the first direction, shaft means (14) integrally extending from the drill means (12) for rotating the drill means (12), drive means (16) attached to said shaft means (14) opposite said drill means (12), characterized by extractor means (20) provided with gripping means (22) for enabling the extractor means (20) to grip the interior of the bore, wherein the shaft means (14) and the extractor means (20) are provided with a thread in the first direction for producing axial displacement of the extractor means (20) along the shaft means (14) towards the drill means (16) and expander means provided adjacent said drill means (12), said expander means comprises a frustroconical shape tapering from the drill means (12) and said extractor means (20) is provided with at least one slot which is provided on the end portion of the extractor means which is faced to the drill means (12), the longitudinal dimension thereof is shorter than the axial dimension of the extractor means (16), wherein said expander means is cooporating with the extractor means (20) for engaging the extractor means and stopping said axial displacement, the expander means expanding the extractor means for gripping the interior of the bore; whereby continued rotation of the drive means in the second direction extracts the fastener from the bore. The tool assembly of claim 1 wherein said drill means (12) is formed of a left-handed drill bit. The tool assembly of claim 2 wherein said threaded shaft means (14) includes righ-hand threads whereby rotation of said drill bit (12) causes rotation of said extractor means (20) in the opposite direction thereof. The tool assembly of claim 1 wherein said extractor means (20) is formed of a plurality of fluted teeth (22).

Inventors: ALDEN CORPORATION
Applicants: ALDEN CORPORATION
Application year: 1987
Main classification: B25B27
IPC codes: B25B27