AU2024203224B1 - Mechanical fastener extractor - Google Patents

Abstract

The invention relates to an extractor for extracting a broken mechanical fastener lodged in a hard substrate.

Description

MECHANICAL FASTENER EXTRACTOR FIELD

[0001] The present invention is directed to an extractor for extracting a mechanical fastener lodged within a hard substrate, particularly for orthopaedic purposes.

BACKGROUND

[0002] Fractured bones require a minimal gap between the bones in order to heal properly and quickly. Mechanical fasteners, such as orthopaedic screws, are often used to anchor or stabilise a bone, either by screwing directly into the bone(s) and/or soft tissue, or via a metal plate 10 which holds the bones together, as shown in FIGURE 1.

[0003] FIGURE 2 shows a variety of types of orthopaedic screws which exist for different purposes, such as: cortical screws for hard bone tissue such as the shaft of long bones; cancellous screws for spongy bones present at the ends; pedicle screws for spine fusion or fractures; cannulated screws which can pass a guide wire through itself for perfect placement of the screw; Herbert screws for internal fixation of broken bones that includes the joint cartilage; and malleolar screws for the fixation of ankle fractures.

[0004] As can occur with all mechanical fasteners, the threads or head of a screw may become damaged or broken during installation or through wear and require removal or replacement. When damaged, extraction via traditional means may not be possible. An example of circumstances in which an orthopaedic screw may become stuck is shown in FIGURE 1. In FIGURE 1, the head 14 of the screw 13 is threaded to engage with the plate 10 in which it is embedded. If the head 14 is screwed into the plate 10 incorrectly, such as through applying too much force, the head 14 can misalign with the plate and become wedged or stuck in the plate 10 and become very difficult to remove when it is time to remove the screw from the body.

[0005] Specific tools for extracting broken screws from bones do exist in the prior art, such as those shown in patent documents US patent 11426226 B2 and US patent application 2022411193 Al. These function by drilling a bore down the centre of the fastener and using a reverse threaded tool to unscrew the fastener. However, such an approach may not always be optimal, particularly with fine fasteners that may break or fracture if a bore is drilled through the middle of the fastener for any length. Also, if the fastener is strongly wedged into a substrate, the thread of the reverse threaded tool may compete with, and ultimately not succeed in, dislodging the thread of the fastener against the substrate.

[0006] US patent 6267025 B1 provides an extractor tool with a tapered threaded internal opening, which cuts around the threaded shank of the screw. The internal thread is of opposite screw thread so that when passing over the screw to be removed, the taper bears against the threaded shank as the extractor is rotated to back the screw out of the substrate. Whilst effective, this extractor is only suitable for screws which have no head and in which the thread shank is compatible with the reverse screw thread.

[0007] US patent application 2004/0154438 Al discloses a device for the extraction of a broken fastener from a workpiece. The device comprises a left-handed drill bit that is surrounded by a socket. The drill bit is configured to drill deep into the mechanical fastener to remove the mechanical fastener while the socket surrounding the drill bit is either (a) designed to maintain a separation of the drill bit from the workpiece; or (b) configured to cut into the workpiece and grip the broken fastener while the drill bit drills into the mechanical fastener. The use of a drill bit to drill deep into the mechanical fastener risks further breaking of the lodged mechanical fastener and further complicating the removal process.

[0008] In view of the above, it would be desirable to provide an extractor of mechanical fasteners which addresses one or more of the issues identified with the prior art above, or at least provides a viable alternative.

[0009] The above discussion of background art is included to explain the context of the present invention. It is not to be taken as an admission that the background art was known or part of the common general knowledge at the priority date of any one of the claims of the specification.

SUMMARY

[0010] According to a first aspect of the invention, there is provided an extractorfor extracting a mechanical fastener, the extractor comprising: a socket, the socket further comprising: a first opening comprising an inner side wall, the inner side wall further comprising one or more gripping projections configured to grip onto or around the head of a mechanical fastener; and a rim around the first opening, the rim comprising a cutting edge for cutting around the head of the mechanical fastener; and an alignment shaft configured to extend from the first opening, the alignment shaft comprising an engagement end configured to screw into the head of the mechanical fastener, wherein the alignment shaft is connected to the socket via a torque-limiting connection such that substantially: the alignment shaft rotates with the socket up to a torque limit; and the socket may rotate relative the alignment shaft on exceeding the torque limit.

[0011] In an embodiment, the cutting edge is a serrated edge.

[0012] In an embodiment, the first opening is tapered to increase the tension of the side wall on the mechanical fastener during rotation of the socket.

[0013] In an embodiment, the, or each, gripping projection is configured to cut into or around the head of the mechanical fastener to improve grip by the socket around the head of the mechanical fastener.

[0014] In an embodiment the alignment shaft extends through the first opening by a distance of up to 1cm.

[0015] In an embodiment, the engagement end comprises a cutting surface configured to cut into the head of the mechanical fastener. In an embodiment, the engagement end comprises cutting flutes. In an embodiment, the cutting flutes extend less than 5mm from the end of the engagement end.

[0016] In an embodiment, the torque-limiting connection is configured such that the socket continues to rotate relative the alignment shaft upon torque applied to the torque-limiting connection returning below the torque limit.

[0017] In an embodiment, the toque-limiting connection comprises an interlocking screw thread arrangement. In an embodiment, the torque-limiting connection comprises a split-pin.

[0018] In an embodiment, the socket is configured to slide along the alignment shaft once the torque limit has been exceeded.

[0019] In an embodiment, the torque-limiting connection is configured such that the socket returns to rotating with the alignment shaft upon the torque applied to the torque-limiting connection returning below the torque limit.

[0020] In an embodiment, the torque limiting connection comprises a friction plate connection. In another embodiment, the torque limiting connection comprises a magnetic connection.

[0021] In an embodiment, the extractor is configured for connection to an electric drill. In an embodiment, the extractor comprises a shank for connection to an electric drill. In an embodiment, the shank extends from an end of the socket opposite the first opening.

[0022] In an embodiment, the extractor comprises a handle enabling manual rotation of the socket. In an embodiment, the handle extends from an end of the socket opposite the first opening.

[0023] In an embodiment, the extractor is configured to arrive at the torque limit once the alignment shaft is suitably embedded in the head of the mechanical fastener. In an embodiment, the torque limit is between 1Nm to 5Nm.

[0024] According to a second aspect of the invention, there is provided a method for extracting a mechanical fastener from a substrate using an extractor according to the first aspect of the invention, the method including: rotating the extractor to screw the alignment shaft into the head of the mechanical fastener until the alignment shaft is embedded in the head of the mechanical fastener; rotating the socket while the alignment shaft is embedded in the head of the mechanical fastener such that the cutting edge cuts into the substrate around the head of the mechanical fastener and the one or more gripping projections grip around the head of the mechanical fastener; and extracting the mechanical fastener.

[0025] Throughout this specification and the claims which follow, unless the context requires otherwise: reference to like numbers denotes reference to like features; the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps; the use of '(s)' following a noun means the plural and/or singular form of that noun. Further, as used herein the term 'and/or' means 'and' or'or', or where the context allows both; reference to "a" or "one" thing, includes a reference to "one or more" of that thing; terms such as "side," "end," "top," "bottom," and the like are only used to describe elements as they relate to one another but are in no way meant to recite specific orientations of the device, to indicate or imply necessary or required orientations of the device, or to specify how the invention described herein will be used, mounted, displayed, or positioned in use; and the reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

BRIEF DESCRIPTION OF THE FIGURES

[0026] The present invention is described by way of non-limiting examples within the following description and figures. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the present invention will suggest themselves without departing from the scope of the present invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. Where specific integers are mentioned herein, which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[0027] FIGURE 1 shows a side view of a plate with mechanical fasteners used for orthopaedic purposes.

[0028] FIGURE 2 shows a variety of mechanical fasteners used for orthopaedic purposes.

[0029] FIGURE 3 shows an extractor according to an embodiment of the invention.

[0030] FIGURE 4 shows an extractor according to another embodiment of the invention.

[0031] FIGURE 5 shows an extractor according to another embodiment of the invention.

[0032] FIGURE 6 shows a process of extracting a mechanical fastener employing the extractor of FIGURE 3.

[0033] FIGURE 7 shows a process of extracting a mechanical fastener employing the extractor of FIGURE 4.

[0034] FIGURE 8 shows a socket for use as an extractor according to an embodiment of the invention.

[0035] FIGURE 9 shows an alignment shaft and engagement end for use as an extractor according to an embodiment of the invention.

[0036] FIGURE 10 shows an extractor having a handle according to an embodiment of the invention.

List of Parts 1 extractor 2 socket 3 alignment shaft 4 first opening cutting edge 6 gripping projections 7 engagement end 8 torque limiting connection 9 sliding connections plate 11 shank 12 handle 13 mechanical fastener 14 fastener head

DETAILED DESCRIPTION

[0037] In broad terms, the present invention provides an extractor for extracting a mechanical fastener with an at least partially recessed head. Within the broader inventive concept, various embodiments of the extractor are described in further detail below with reference to FIGURES 3-10.

[0038] FIGURE 3 shows an extractor 1 according to an embodiment of the invention. In the embodiment shown, the extractor 1 is configured for use with an electric drill and is provided with a shank 11 for connection to an electric drill, enabling the extractor 1 to be driven by the drill. In the embodiment shown, the extractor 1 is configured to be rotated or driven in a counter-clockwise direction to enable extraction of mechanical fasteners, such as screws, that are by convention configured to be extracted in a counter-clockwise direction. Broadly speaking, the extractor 1 comprises a socket 2 surrounding an alignment shaft 3 for aligning the socket to a mechanical fastener. The socket 2 is provided with a first opening 4 having gripping projections 6 along an inner wall of the first opening 4 (best exemplified in FIGURE 7) and a cutting edge 5 along the rim of the first opening 4 (again, best exemplified in FIGURE 7). The socket 2 is thereby able to cut into the substrate around the head of an embedded mechanical fastener and grip around the head of the mechanical fastener to assist in extracting the mechanical fastener from the substrate.

[0039] In certain embodiments, the first opening 4 is tapered with the taper narrowing as it veers away from the rim and the cutting edge 5, such that the gripping projections 6 are better able to grip onto the head of a mechanical fastener as the head advances into the first opening 4 of the socket 2 (see for example FIGURES 3-6). Whilst rounded hexagonal gripping projections 6 are exemplified in FIGURE 7, any shaped projections may be suitable provided they grip around the mechanical fastener. In the embodiment shown in FIGURE 7, the cutting edge 5 is a serrated edge. However, in other embodiments, the cutting edge may for example be a sharpened edge. Which arrangement is optimum would generally depend on the nature and hardness of the substrate in which the mechanical fastener is lodged.

[0040] Extending from the first opening 4 is the alignment shaft 3. The alignment shaft 3 is provided to enable alignment of the socket 2 about the head of a mechanical fastener such as a screw. Such an arrangement is particularly useful in circumstances where the head of the mechanical fastener is recessed into the substrate such that it may otherwise be difficult to align the socket 2 to the head of the mechanical fastener. The alignment shaft 3 is intended to screw into the head of the mechanical fastener and lodge or embed therein. For this purpose, the alignment shaft 3 comprises an engagement end 7 intended to engage with the head of a mechanical fastener, such as by screwing or drilling into the head of the mechanical fastener. An embodiment of a suitable engagement end 7 is exemplified in FIGURE 9. As exemplified in FIGURE 9, the engagement end 7 may constitute a shortened drill bit comprising a cutting surface formed of short flutes. The purpose of providing short flutes is that the engagement end 7 of the alignment shaft 3 should dig into the head of the mechanical fastener, but only as far as the flutes are provided. At that point the alignment shaft 3 should receive increased resistance to any further drilling into the head of the mechanical fastener. Further drilling into the head of the mechanical fastener risks breaking or weakening the head of the mechanical fastener, which may in turn make it more difficult to remove the mechanical fastener from the substrate. According to certain embodiments, the flutes may only extend up to 5mm from the tip of the engagement end 7, so that the engagement end 7 only lodges or embeds up to 5mm into the head of the mechanical fastener. As shown in FIGURES 3-5 and FIGURE 9, the flutes may be configured to cut in a counter-clockwise direction, in alignment with a socket 2 that is likewise configured to cut in a counter-clockwise direction. Such an arrangement is best suited to extraction of mechanical fasteners which screw into a substrate in a clockwise direction. For extraction of mechanical fasteners which screw into a substrate in an anti-clockwise direction, an extractorwhich extracts in a clockwise direction may be more appropriate according to certain embodiments of the invention. According to certain embodiments, the alignment shaft 3 extends no more than 1cm out from the first opening 4. This is fundamentally because such a distance is all that is needed to enable the alignment shaft 3 to engage and align with a mechanical fastener.

[0041] Operation of the torque limiting connection 8 is now explained. The torque limiting connection 8 connects the alignment shaft 3 to the socket 2, and effectively works as a coupling that enables rotation of the socket 2 to drive rotation of the alignment shaft 3 (when low levels of torque act on the torque limiting connection 8). This enables a drill engaging the extractor 1 of FIGURE 3 via shank 11 to drive the alignment shaft 3 of the extractor 1 (at low levels of torque acting upon the alignment shaft 3). At higher levels of torque acting upon the alignment shaft, rotation of the socket 2 will cease to drive rotation of the alignment shaft 3. For example, if the alignment shaft 3 is embedded into the head of a mechanical fastener, rotation of the socket 2 will cease to drive rotation of the alignment shaft 3 (and the alignment shaft will continue to be embedded in the head of the mechanical fastener).

[0042] A number of potentially suitable torque limiting connections would be known to the person skilled in the art. For example, a simple torque limiting connection may be formed of a shear pin configured to break at a predetermined torque and thereby disengage the alignment shaft 3 from the socket 2. Such an arrangement is exemplified in FIGURE 5 in which a split pin 8 is arranged to pass through both the socket 2 and the alignment shaft 3. At low levels of torque, the split pin 8 will drive rotation of the alignment shaft 3 upon rotation of the socket 2. The split pin 8 may be considered a destructive form of torque limiting connection, in that the split pin 8 will require replacement upon breaking.

[0043] In FIGURES 3 and 4, the torque limiting connection is formed of a cooperating threaded connection that effectively operates to drive rotation of the alignment shaft 3 through static friction. That is, at low levels of torque the components forming the torque limiting connection will have sufficient static friction between them to enable rotation of the alignment shaft 3 to drive rotation of the socket 2. At higher levels of torque however, the components of the torque limiting connection 8 will commence to unscrew from one another whereby the alignment shaft 3 will not rotate along with the socket 2. In the extractor 1 of FIGURE 3, only a small amount of rotation is necessary to effectively disengage the torque limiting connection 8 by complete unwinding of the torque limiting connection 8. Upon complete unwinding, the alignment shaft 3 is slidingly held in place within the socket 2 by sliding connections 9, until the torque limiting connection 8 is effectively reengaged by rewinding. In the extractor 1 of FIGURE 4, the extent of the cooperating threaded connection is longer than that of FIGURE 3 and the torque limiting connection 8 is not configured to completely unwind. Rather, it is exclusively the continued unwinding of the torque limiting connection 8 that enables the alignment shaft 3 to remain "still" while the socket 2 rotates. However, the torque limiting connection 8 may require re-setting from time to time by effectively rewinding the torque limiting connection 8 to a fully wound position. As shown in FIGURES 3 and 4, the torque limiting connection 8 is configured to 'unwind' in a counterclockwise direction.

[0044] Other torque limiting connections are also envisaged such as those described on Wikipedia under the article "Torque Limiter" (https://en.wikipedia.org/wiki/Torque limiter). Such arrangements may for example involve static plates that operate much like the drag clutch mechanism in a fishing reel, for example. What may be used may be limited by matters such as size, complexity, and manufacturing. According to certain embodiments, the torque limiting connection is configured to operate to a pre-determined torque limit. Such a torque limit should ideally align with the torque that would be applied to the alignment shaft 3 when the alignment shaft is properly embedded into the head of a mechanical fastener. A suitable torque limit may for example be 1-5 Nm depending upon the design of the alignment shaft and of the relevant mechanical fastener.

[0045] Operation of an extractor 1 to extract a mechanical fastener is now described with reference to FIGURE 5. FIGURE 5A shows an extractor 1 ready for use adjacent a mechanical fastener 13, in this case a screw. While not shown in FIGURE 5A, the screw 13 is lodged within a substrate. The torque limiting connection 8 is'armed'such that, at low torque, rotation of the socket 2 will drive rotation of the alignment shaft 3. As shown in FIGURE 5B, the alignment shaft 3 effectively operates as a drill to drill into the head 14 of the screw 13, but only until the flutes of the engagement end 7 are embedded into the head 14 of the screw 13, at which point resistance to further drive the engagement end 7 into the head 14 of the screw 13 will increase and the engagement end 7 will be effectively embedded into the head 14. At that point the torque limiting connection 8 will unwind as the socket 2 rotates while the alignment shaft 3 does not rotate. In the embodiment shown in FIGURE 5, the torque limiting connection 8 will once 'unwound' disengage such that the alignment shaft 3 will sit freely within the socket 2 via sliding connections 9. At this point the socket 2, aligned with the head 14 of the screw 13, by the alignment shaft 3, is free to effectively 'drill' onto the head 14 whereby the gripping projections 6 grip around the head 14 to remove the screw 13 from the substrate.

[0046] The extractor 1 shown in FIGURE 6 operates much like that shown in FIGURE 5. However, in the extractor 1 of FIGURE 6, the torque limiting connection 8 is not configured to completely disengage by unwinding. Rather, it is the unwinding of the torque limiting connection 8 that allows the alignment shaft 3 to remain 'still'while the socket 2 rotates (such as when driven by a drill). Such an embodiment would work well with soft substrates in which the cutting edge 5 of the socket 2 is able to dig into the substrate at the same or greater rate as the socket 2 winds relative the alignment shaft 3 toward the substrate. Otherwise, if the substrate is too hard and the cutting edge 5 may not cut into the substrate fast enough, rotation of the socket 2 may result in the alignment shaft 3 being pulled from the head 14 of the mechanical fastener 13. Such an arrangement may still work however if the engagement end remains within the cavity created in the head of the mechanical fastener.

[0047] More generally it may be useful to ensure that the socket 2 is able to move down the alignment shaft 3 (whether in a fixed or free fashion) once the alignment shaft 3 is embedded in the head 14 of the mechanical fastener 13 such that the socket 2 is able to engage the substrate and the head of the mechanical fastener 13 to extract the mechanical fastener 13. Arrangements to provide for such movement need not however necessarily be linked to or form part of the torque limiting connection 8.

[0048] According to certain embodiments of the invention, the extractor 1 may be configured to connect to a standard drill, such as by, for example, comprising a shank 11 for connection to a standard drill. In other embodiments, extractor 1 may for example comprise a handle 12 enabling manual screwing of the extractor into the substrate around the mechanical fastener 13. Such an arrangement is exemplified in FIGURE 10.

[0049] While the extractor 1 may according to certain embodiments be particularly suited for removal of mechanical fasteners from human and animal bones, in other embodiments the extractor it may be suitable for extracting mechanical extractors from other materials such as metal, plastic, or wood. The extractor 1 may be formed of a number of suitable materials, including by having particular components made of different materials. According to certain embodiments, the extractor may be generally or substantially formed of a metal, such as stainless steel. In certain applications the metal may be a harder or hardened metal such as a tungsten carbide-based steel. Such materials are particularly suited to use in extracting a mechanical fastener from a hard substrate such as a metal substrate.

[0050] FIGURE 7 shows how when the socket 2 is rotated, the cutting edge 5 cuts into the substrate and the gripping projections 6 in the first opening 4 grip onto the head of a mechanical fastener 13, such as a screw. Once the gripping force is sufficient, the socket 2 is able to grip onto the head of the mechanical fastener 13 and remove the mechanical fastener 13 upwards and out of the substrate, such that the socket 2, mechanical fastener 13, and minimal surrounding substrate are removed.

[0051] According to alternative embodiments, particularly where the substrate is formed of a hard material similar to the fastener or screw, the extractor may be used to cut and form a separate surrounding region of the substrate about the head of the fastener, which is then gripped onto by the socket and removed along with the fastener. For example, with reference to FIGURE 1, an extractor may be used to cut a surrounding region of the plate forming the substrate, and since the head of the screw shown in FIGURE 1 is lodged within the plate, removal of the surrounding region may result in removal of the screw.

[0052] According to further embodiments, the socket of the invention may comprise a means to contain shavings caused by use of the cutting edge of the socket. For example, the socket may comprise a cover or hood which surrounds the cutting edge of the socket in contact with the substrate. The containment means may be configured as a truncated cone, with the narrow end arranged to generally surround the cutting edge in contact with the substrate (much in the shape of an Elizabethan collar). In use, the containment means is placed around the lodged fastener head prior to commencing cutting using the cutting surface. Once a fastener has been extracted and the cutting edge has been removed from the substrate, a vacuum tube can for example then be utilised within the region contained by the containment means to extract metal shavings and the containment means can be removed. Such an approach may have particular application in surgery when removing surgical screws.

[0053] It will be understood to persons skilled in the art of the invention that modifications may be made without departing from the spirit and scope of the invention. The embodiments and/or examples as described herein are therefore to be considered as illustrative and not restrictive.

Claims (17)

1. CLAIMS 1. An extractor for extracting a mechanical fastener, the extractor comprising: a socket, the socket further comprising: a first opening comprising an inner side wall, the inner side wall further comprising one or more gripping projections configured to grip onto or around the head of a mechanical fastener; and a rim around the first opening, the rim comprising a cutting edge for cutting around the head of the mechanical fastener; and an alignment shaft configured to extend from the first opening, the alignment shaft comprising an engagement end configured to screw into the head of the mechanical fastener, wherein the alignment shaft is connected to the socket via a torque-limiting connection such that substantially: the alignment shaft rotates with the socket up to a torque limit; and the socket may rotates relative the alignment shaft on exceeding the torque limit.
2. 2. An extractor according to claim 1, wherein the cutting edge is a serrated edge.
3. 3. An extractor according to either of claim 1 or claim 2, wherein the first opening is tapered.
4. 4. An extractor according to any one of the previous claims in which the, or each, gripping projection is configured to cut into or around the head of the mechanical fastener.
5. 5. An extractor according to any one of the previous claims, wherein the alignment shaft extends through the first opening by a distance of up to 1 cm.
6. 6. An extractor according to any one of the previous claims, wherein the engagement end comprises a cutting surface configured to cut into the head of the mechanical fastener.
7. 7. An extractor according to claim 6, wherein the engagement end comprises cutting flutes.
8. 8. An extractor according to claim 7, wherein the cutting flutes extend less than 5mm from the end of the engagement end.
9. 9. An extractor according to any one of the previous claims, wherein the torque-limiting connection is configured such that the socket continues to rotate relative the alignment shaft upon the torque applied to the torque-limiting connection returning below the torque limit.
10. 10. An extractor according to any one of the previous claims, wherein the torque-limiting connection comprises an interlocking screw-thread arrangement.
11. 11. An extractor according to any one of claim1toclaim 9, wherein the torque-limiting connection is configured such that the socket to returns to rotating with the alignment shaft upon the torque applied to the torque-limiting connection returning below the torque limit.
12. 12. An extractor according to any one of the previous claims, wherein the socket is configured to slide along the alignment shaft once the torque limit has been exceeded.
13. 13. An extractor according to any one of the previous claims, wherein the extractor is configured for connection to an electric drill.
14. 14. An extractor according to any one of claim 1 to claim 12, wherein the extractor comprises a handle enabling manual rotation of the socket.
15. 15. An extractor according to any one of the previous claims, wherein the torque limit is between 1Nm to 5Nm.
16. 16. A method for extracting a mechanical fastener from a substrate using an extractor according to any one of claims 1 to 15, the method including: rotating the extractor to screw the alignment shaft into the head of a mechanical fastener until the alignment shaft is embedded in the head of the mechanical fastener; rotating the socket while the alignment shaft is embedded in the head of the mechanical fastener such that the cutting edge cuts into the substrate around the head of the mechanical fastener and the one or more gripping projections grip around the head of the mechanical fastener; and extracting the mechanical fastener.
17. 17. A method according to claim 16, comprising using a drill to rotate the extractor.

    FIGURE FIGURE 11 May 2024

    14 14

    PRIOR ART PRIOR ART 10 10 2024203224

    13 13

    FIGURE FIGURE 22

    PRIOR ART PRIOR ART

    1/5 1/5

    FIGURE33 May 2024

    FIGURE

    9 9 2 2 7 7 2024203224

    3 3 8 11 8 9 11 9 FIGURE FIGURE 44 4 4 5 5

    8 8 FIGURE55 FIGURE

    9 9 9 9 12 12

    2/5 2/5

    FIGURE FIGURE 66 May 2024

    7 7 2024203224

    5A 5A 13 13

    14 14

    5B 5B 7 8 8 7

    5 5

    9 9 9 9 6 6 5C 5C

    3/5 3/5

    FIGURE FIGURE 77 May 2024 2024203224

    8 8 6A 6A

    6B 6B

    6C 6C

    4/5 4/5

    FIGURE88 May 2024

    FIGURE

    5 5

    2 2 2024203224

    6 6

    FIGURE99 FIGURE

    FIGURE 10 FIGURE 10

    3 3 7 7

    4 4 12 12

    1 1

    5/5 5/5