Device for installing an insert

Abstract

Device for Installing an Insert The invention relates to a device (100) for installing an insert (200) provided with one or more keys (9) into a surface. The device comprises - a housing (10) with an inner body (20) arranged therein, both having a same central longitudinal axis (AA), said inner body having at one end a strike surface (24), - an outer body (30) comprising a central protrusion (2) for positioning said insert on, said central protrusion centred around the central longitudinal axis, said outer body being movable along the central longitudinal axis and comprising an outer surface (32) provided with at least one hole (34) for receiving a key, - further guiding means (4) having an axis parallel to the central longitudinal axis and arranged to align with the key when the key is received in said hole, so that when an impact force is applied to the strike surface the further guiding means drives the key in position. The further guiding means are chamfered and orientated and protrude from said outer surface (32).

Description

Device for Installing an InsertField of the invention

[0001] The present invention is generally related to the field of tools to ease the installation of inserts provided with locking keys.Background of the invention

[0002] A threaded insert is a fastener element that is inserted into an object to add a threaded hole. It is often necessary, particularly in the aircraft industry, to install a high strength externally and internally threaded insert in relatively soft material in order to increase the holding power of a fastener in the soft material. Such inserts often have longitudinally advanceable keys that mechanically lock the insert in the relatively soft material. Heretofore, the keys have been driven to the locked condition along the grooves in the threaded insert by a secondary operation which, in most instances, consists of merely hammering the keys into position.

[0003] Key locking inserts are commonly used broadly in industry to provide a replaceable threaded attachment point (typically to a metal workpiece). A particular situation is in gas turbine engines (broadly including turbofans, turbojets, turboprops, turboshafts, and industrial gas turbines), typically to attach external components to case pieces of the engine (e.g., pipe hangers, accessories, and the like).

[0004] Fig.l illustrates such a key locking insert, also briefly referred to hereinafter as insert. The insert (200) comprises an insert body or "bushing body" extending along a central longitudinal axis, that is installed by being screwed in, and one or more keys (9) that are crimped during the installation so as to prevent any loosening or unscrewing of the insert. A key is crimped by striking it axially so as to cause the key to penetrate by force between the insert and the hole into which said insert has been screwed.

[0005] Various tools have been proposed in the art to install such key locking inserts, in other words to keep the insert in place and to hammer the keys. A number of shortcomings to the existing solutions can however be indicated. For example, there are no means provided to guide or limit the rotation of certain types of device, which may cause a key to be driven in at an angle instead of straight, causing the key to bend. This is very detrimental to the resulting quality of the installation. Further, during installation by means of the tool care has to be taken not to damage the surface into which the key locking insert is placed.

[0006] In CN202162773U a keyed self-locking installation tool is presented comprising a positioning sleeve. On one end of the positioning sleeve an inner hole is provided, which is used toconnect with the keyed self-locking screw to be installed. A keyway communicating with the inner hole is arranged on the end surface of the positioning sleeve where the inner hole is located. The installation tool also includes a cylindrical pin, which is installed at the end of the positioning sleeve opposite to the connecting interface and serves as a handle for rotating the tool.

[0007] Patent US6704985B discloses a threaded insert tool that properly aligns and inserts a threaded insert into a tapped bore and simultaneously protects the locking keys from damage. During the installation process the threaded insert is slid onto a pilot of the tool and the locking keys on the insert are received in the corresponding tool keyways on the body of the tool. The lower end of the insert is then inserted and screwed into the bore. The tool is then lifted upward from the insert to release the locking keys from the tool keyways. Then the body of the tool is used to bring the upper ends of the keys into key retaining means. Next a suitable impact tool is used to provide an impact force against the strike end of the tool that is sufficient to drive the locking keys down into the tapped bore. So, a two-step approach is adopted to hammer the keys into their final position. Hence, improvements in terms of installation efficiency may be desirable. The solution proposed in US6704985B further suffers from the drawback that when striking the keys under an angle, this may cause the keys to bend. This obviously compromises the overall quality of the installation.

[0008] In CN110450100 A an integrated key-locking threaded insert mounting device is disclosed. Four guide keys are arranged at the front section of a guide rod and matched with the four guide grooves inside a sleeve, the spring and the stop block penetrate through the rear end of the guide rod. Using the device, plug pins can be quickly and continuously embedded in the installation process by virtue of spring rebounding reset. However, the device is not adapted for performing an installation just below the upper surface of the workpiece.

[0009] There is thus a need for an improved device for installing a key-locked insert.Summary of the invention

[0010] It is an object of embodiments of the present invention to provide for a device that overcomes one or more of the above-mentioned drawbacks of the prior art solutions. More in particular, the device according to the invention overcomes the drawback that keys tend to bend when being hammered into the surface. Furthermore, it is desirable to have a device that allows for an installation under the surface of the workpiece.

[0011] The above objective is accomplished by the solution according to the present invention.

[0012] In a first aspect the invention relates to a device for installing an insert provided with one or more keys into a surface, comprising- a housing with an inner body arranged therein, said housing and said inner body having a same central longitudinal axis, said inner body having at one end a strike surface,- an outer body at least partially outside the housing comprising a central protrusion for positioning the insert on, said central protrusion being centred around said central longitudinal axis, said outer body being slidably movable along the direction of the central longitudinal axis and comprising an outer surface provided with at least one hole for receiving one of the keys,- further guiding means between the outer body and the inner body, said further guiding means having an axis parallel to the central longitudinal axis and being arranged to align with said one key when that one key is received in the hole, so that when an impact force is applied to the strike surface the inner body drives via the further guiding means said key into its final position in the surface. The device is characterized in that the further guiding means protrude from the outer surface and have a chamfered edge. The further guiding means are at the end near the inner body shaped to prevent rotation of the further guiding means.

[0013] The proposed solution indeed allows for hammering a key of the insert into the surface without risk of damage due to bending. Between the inner and outer body the further guiding means is provided, oriented in parallel with the central longitudinal axis and aligned with the key when said key is received in the hole of the outer surface of the outer body. The further guiding means so make sure the key can only move in the same direction as the further guiding means. Moreover, due to the specific shape of the end of the further guiding means extending from the outer surface it is possible to install the insert just below the upper surface of a workpiece.

[0014] It is an advantage of the invention that the one or more keys of the insert can be hammered under the correct angle, thereby completely preventing bending of the key(s) or misalignment of the device.

[0015] It is an advantage of the invention that the device can assure a proper installation of the insert without any risk of damage. Due to providing the chamfer the amount of surface of the device in contact with the upper surface of the workpiece is kept minimal.

[0016] It is an advantage of the invention that the device can perform installations of threaded inserts with a repeatable high quality. The installation success rate of may be very high, even as high as 100%.

[0017] Advantageously, the further guiding means comprise at least two pins.

[0018] In preferred embodiments the outer body and the inner body are arranged to have a spring in between. This makes sure that after installation the outer body comprising the central protrusion returns to its original starting position. This improves the ease of use of the device.

[0019] In a preferred embodiment the further guiding means has a T-shaped outer end near said inner body. This fixes the further guiding means and prevents movement.

[0020] Preferably the inner body is at least partially threaded.

[0021] In some embodiments the inner body is at one end provided with an impact cap.

[0022] In some embodiments the outer body comprises a central guiding means extending from the outer body towards the inner body and centred around the central longitudinal axis.

[0023] In an embodiment the central guiding means has a T-shaped outer end near the inner body when looked at in side view. This shape offers the advantage of avoiding rotation of the device.

[0024] In another embodiment, the housing is provided with a recess in which a screw is attached to the outer body. The freedom of movement of the outer body in the direction of the central axis is thus limited in accordance with the freedom of movement of the screw within the recess.

[0025] For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0026] The above and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.Brief description of the drawings

[0027] The invention will now be described further, by way of example, with reference to the accompanying drawings, wherein like reference numerals refer to like elements in the various figures.

[0028] Fig.l illustrates a threaded insert as commonly known in the art.

[0029] Fig. illustrates an embodiment of the device according to the invention.

[0030] Fig.3 illustrates an embodiment of the outer body of the device.

[0031] Fig.4 illustrates some view of the further guiding means provided with a chamfer.

[0032] Fig.5 illustrates a view on the inner body with at one end an impact cap.

[0033] Fig.6 illustrates an embodiment with a spring between the inner body and the outer body.

[0034] Fig.7 illustrates the bottom surface of the outer body comprising a recess for the spring shown in Fig.6 in the lower part of the figure, while the upper part illustrates a side view on the T-shaped

[0035] Fig.8 illustrates the position of the pins before and after the hammering.

[0036] Fig.9 illustrates the process of driving the locking keys into the surface by means of the device according to the invention.

[0037] Fig.10 illustrates another embodiment of the device according to the present invention.

[0038] Fig.11 illustrates the central guiding means having a T-shaped extremity.

[0039] Fig.12 illustrates the recess and the screw mounted therein.Detailed description of illustrative embodiments

[0040] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0041] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0042] It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0043] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment but may. Furthermore, theparticular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0044] Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0045] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0046] It should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to include any specific characteristics of the features or aspects of the invention with which that terminology is associated.

[0047] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0048] The present invention discloses a device (100) to assist in the installation of a threaded insert having one or more keys. The insert is typically as shown in Fig.l. Conventionally the insert contains two or four locking keys. In the context of the present invention key-locking inserts are considered that are not limited to a specific number of keys. An insert may have one or two or four keys or any other number of keys. The device of the invention is preferably implemented as a hand tool. However, in some embodiments the concept on which the device is based, can easily be adapted to be mounted on a power tool, possibly a portable power tool. Later in the description more details are provided.

[0049] An embodiment of a device (100) according to the present invention is shown in Fig. . The left-hand part of the figure shows an outer view of the device and the right-hand part a crosssection along the line AA. The device comprises a housing (10). In the housing is provided an inner body (20). The housing and the inner body have a same central axis in longitudinal direction, corresponding to the line AA in the figure. In preferred embodiments (for example, as depicted in Fig.2) the housing is substantially cylindrically shaped, but the invention is in no way limited thereto. The outer shape of the housing may be of any suitable form. In some cases, it may for example be desirable that the housing of the tool be rectangular or octagonal in shape or have a locating indentation. The inner body comprises at one end a strike surface (24).

[0050] At least partially outside the housing one finds an outer body (30). The outer body can be seen as a plunger. The outer body comprises at one end a central protrusion (2). On this central protrusion the insert is positioned during the installation. The central protrusion (2) is centred around the same central longitudinal axis as the housing (10) and the inner body (20). The outer body can slidably move over a certain distance along the direction of that central axis. The outer body has an outer surface (32) wherein at least one hole (34) is provided. In preferred embodiments the outer surface contains two or four holes. The outer surface can be seen as the insertion end of the device and is also the surface from which protrudes the cylindrical central element (2) (sometimes also named pilot) on which the insert is to be positioned during the installation. The at least one hole is a bored keyway for a key of the insert. In each hole one of the keys of the insert can be received. As also illustrated in Fig.2, only a limited portion of the outer body (30) extends outside the housing. Specifically, the outer surface (32) and the central protrusion (2) are always located outside the housing (10). The remainder of the outer body (i.e., the plunger) is usually largely within the housing in this embodiment. This depends on the movement made during the installation process. In some embodiments the outer body consists of two parts, whereby the part (33) is provided as a separate entity between the actual outer body and the inner body. In other embodiments the part (33) is integrated in the outer body.

[0051] As already mentioned, in advantageous embodiments the outer surface may have two holes, meaning that two keys can be received. This is illustrated in Fig.2. The centres of the two holes are then preferably 180° apart from one another, i.e. the holes are positioned on opposite sides of the central protrusion. Also the outer body is in preferred embodiments cylindrically shaped. Fig.3 provides an illustration in top view and cross-section view of the outer body with the central protrusion and two holes for receiving insert keys. The invention is however not at all limited to a cylindrically shaped outer body, and other shapes than cylindrical may occur equally well. There is noteven a strict need for the outer body to have a same shape as the housing. In advantageous embodiments however the housing and the outer body substantially have a same or similar shape.

[0052] The outer diameter of the central protrusion (2) corresponds to the inner thread diameter of the threaded insert, and the length of the central protrusion preferably corresponds approximately to the length of the insert body. The distance from said central longitudinal axis to the nearest edge of a hole corresponds to the radius of the upper face of the outer thread on the threaded insert, so that the one or more keys are receivable in the hole when the insert is positioned on the central protrusion.

[0053] In order to solve the problem of bending keys during the installation process, the device of the invention comprises in the outer body further guiding means (4) having an axis in parallel to the central longitudinal axis. The further guiding means are so positioned that they align with the one or more keys received in the holes. In the embodiment of Fig.2 the further guiding means are implemented as two pins, corresponding to the two holes present in that embodiment. The holes (34) in the outer surface are so shaped that the further guiding means (4), i.e. the pins, can pass through. Hence, given that the pin is aligned with the respective key when the latter is received in the hole, the pin drives the key into the surface wherein the insert is to be installed when an impact force is applied to the strike surface of the device, for example by hitting with a hammer.

[0054] The top surface of the further guiding means (4) that can extend from the outer surface (32) is provided with a chamfer, i.e. one side has a slightly sloping edge. The slope (e.g., 30° or 45° without being limited thereto) ascends from the outer surface in the direction of the central longitudinal axis. This feature offers several interesting benefits. Contact of the further guiding means with the counterbore is so avoided. During installation the amount of surface of the outer body that immediately contacts the surface wherein the insert is to be installed is so reduced, thereby decreasing the risk of damaging that contact surface. Further, due to the chamfered shape at the one end of the further guiding means it becomes possible to install the insert below the surface where the insert is installed, for example 0.2 mm or 0.3 mm or 0.4 mm or 0.5 mm or 0.6 mm or 0.7 mm below, depending on the specific requirements. In certain industries (like the aircraft industry just to name one example) it is required to have the inserts installed below the surface so that the installed insert does not stick out of the surface. The shape of the further guiding means is illustrated in Fig.4. Two side views illustrating the T-shape are shown as well as a top view.

[0055] In an implementation with four holes in the outer surface of the outer body obviously up to four keys can be received in the respective holes at a time. The further guiding means (4) then consist of four pins, positioned around the central protrusion and preferably spaced substantially 90° apart from each other. Each pin is shaped as described above and illustrated in Fig.4.

[0056] In preferred embodiments the inner body is at least partially threaded. Due to the threaded part (25) the inner body can be threaded into the housing and hold the further guiding means into place. The threading of the inner body is illustrated in Fig.2.

[0057] In some embodiments the housing near the strike surface and the end of the inner body is made somewhat broader. This is also the case in Fig.2. This yields the advantage that an impact cap (3) with a broadened strike surface is obtained so that it is made easier to exert a suitable impact force to the inner body. Fig.5 illustrates the inner body with impact cap. The central longitudinal axis is indicated. At the top of the figure a bottom view is provided.

[0058] In preferred embodiments a spring (45) is provided between the outer body and the inner body. This makes sure that after the installation of the insert the outer body (30) returns to its initial position, ready for the next installation. An illustration is given in Fig.6. In some embodiments a recess (39) is provided in the surface (37) of the outer body opposite the outer surface (32) to receive one end of the spring, as shown in Fig.7 where the bottom part depicts a view of the bottom surface of the outer body. Apart from the recess (39) the figure shows two holes for receiving the extremity of the further guiding means. This end is so shaped that rotation is prevented (see also Fig.4). In embodiments where the outer body comprises a separate part (33) as mentioned above, the recess may be replaced by a bore.

[0059] The process of installing the threaded insert with the tool of the present invention is now described. The threaded insert is slid onto the central protrusion (2), moved toward the outer surface (32) of the outer body (30), and simultaneously arranged so that the locking key(s) (9) on the insert is / are received in the corresponding hole(s) (34) on the outer body. The lower end of the threaded insert is then inserted and screwed into the bore. This may be done either using the device of the invention or manually. The insert is screwed until the insert is completely threaded into the bore. The upper ends of the one or more locking keys stick out above the surface and still need to be hammered into the surface. This is done with the device. The outer body is in a position as shown in the left-hand part of Fig.8. Note that for clarity reasons the insert with its locking key(s) is not shown in this figure. Again, an embodiment is shown where the outer body comprises two holes and the further guiding means (4) consist of two pins. The pins are about to be received into the holes (i.e. the round bores) in this embodiment. When an impact force is applied to the device, more in particular to the strike end of the device, the housing comprising the inner body moves forward towards the outer body, whereby the pins are pushed through the holes and the lower surface of the outer body touches the housing or, if present, the spring between the outer body and the inner body is compressed. The right-hand part of Fig.8 shows the top of the further guiding means extending from the housing. The impact force can be applied by hand (e.g., tapping or punching) or with anappropriate tool like a hammer, a semi-automatic or automatic device to hit the striking face, or the like.

[0060] The effect of the impact is illustrated more in detail in Fig.9, which, again, considers a case with two holes in the outer surface and thus two pins. In the left-hand part of the figure the device is brought in the right position to hammer the partially sticking out keys into the surface of the workpiece. As can be seen in the figure the pins are aligned with the respective keys. The right-hand part of the figure shows the situation after the keys have been driven into the surface. Due to the impact the housing has moved downwards in the direction of the surface, thereby forcing the upper ends of the locking keys down into the bore until they are flush with the upper edge of the threaded insert.

[0061] In some embodiments the further guiding means (4) is so shaped that its outer end near the inner body has a T-shape when looked at in side view. The top part of Fig.7 provides an illustration, similar to what was already shown in Fig.4. The collar may for example have a square or rectangular shape in order to prevent movement (rotation) of the further guiding means. Alternatively, any other shape that prevents rotation can be employed. An illustration is provided in the bottom part of Fig.7, where the collar has a D-shape.

[0062] An alternative to the embodiment of the device (100) according to Fig. is shown in Fig.10. This embodiment is very similar to that of Fig.2, but with the main difference that there is a central guiding means (5), which extends from the inner body towards the outer body. This is shown in Fig.10. Further note that the outer body (i.e. the plunger) is now positioned more outside of the housing than in Fig.2. The outer surface (32) of the outer body still includes at least one hole (34) for receiving one of the keys. The one or more holes in the outer surface extend to the surface of the outer body opposite the outer surface (32), so that the further guiding means (in other words the pins) can pass through. The embodiment of Fig.10 also exhibits the previously mentioned features of the at least partially threaded inner body and the slight widening of the inner body near the striking face. The central guiding means maintains a fixed position with respect to the rest of the outer body. The central guiding means is fixed to the rest of the outer body, for example by gluing. The central guiding means (5) is centred around the same central longitudinal axis as the housing (1) and the inner body (20).

[0063] In some embodiments with a central guiding means (5), this central guiding means is shaped such that its outer end near the inner body has a T-shape. An illustration is given in Fig.11. The figure shows two side views as well as a top view. As the figure illustrates, the central guiding means has a collar of suitable shape on the T-shape to secure the guiding means. For example, this shape issquare or rectangular, without being limited thereto. By using the central guiding means with such a T-shaped end, rotation of the device during use is prevented.

[0064] Fig.12 illustrates an embodiment in which the housing has a recess (slot) (17) containing a sliding screw (19). This is screwed into the outer body (30). This prevents the outer body from falling out of the housing. The slot's main direction is parallel to the central axis, as can be seen in the figure (axis BB). The length of the slot determines the distance the screw (and the connected outer body) can move. In other words, the limited movement distance of the screw in the slot limits the distance the outer body can move in the direction of the central axis.

[0065] The installation process described previously remains largely the same. The positioning remains as explained above. When a thrust force is applied to the device of the invention, the inner body, along with the housing and pins, moves forward toward the outer body, pushing the pins through the holes. As the pins align with their respective keys, the ends of the locking keys are pressed down into the bore, as previously described.

[0066] In preferred embodiments the threaded insert tool can be made of surface-hardened steel, or of stainless steel or a combination of those materials. Any other suitable material may be employed instead. It shall be understood that any material that is suitable for the particular intended application of the tool may be used.

[0067] It was already set out above that the central protrusion has an outer diameter corresponding to the inner thread diameter of the threaded insert, and a length corresponding approximately to the length of the insert. Hence the device of the invention is tailored to a specific type of insert. The device is available in different formats, each corresponding to an insert with specific dimensions.

[0068] The device is commonly used as a hand tool. The same principles as described above can however be applied to a power tool arranged to receive at its front side an outer body as described above. The power tool is adapted to be provided with the further guiding means (pins) as described above. The further guiding means are controlled by the motor of the power tool. Instead of a power tool a pneumatic or hydraulic tool can be employed.

[0069] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways. The invention is not limited to the disclosed embodiments.

[0070] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Claims

Claims1. Device (100) for installing an insert (200) provided with one or more keys (9) into a surface, comprising- a housing (10) with an inner body (20) arranged therein, said housing and said inner body having a same central longitudinal axis (AA), said inner body having at one end a strike surface (24),- an outer body (30) at least partially outside said housing comprising a central protrusion (2) for positioning said insert on, said central protrusion being centred around said central longitudinal axis, said outer body being slidably movable along the direction of said central longitudinal axis and comprising an outer surface (32) provided with at least one hole (34) for receiving one of said keys, - further guiding means (4) between said outer body and said inner body, said further guiding means having an axis parallel to said central longitudinal axis and being arranged to align with said one key when said one key is received in said hole, characterized in that said further guiding means protrude from said outer surface (32) and have a chamfered edge, and are at the end near said inner body shaped to prevent rotation of said further guiding means.

2. Device as in claim 1, wherein said further guiding means comprise at least two pins.

3. Device as in any of the previous claims, wherein said outer body and said inner body are arranged to have a spring (45) in between.

4. Device as in any of the previous claims, whereby said further guiding means has a T-shaped outer end near said inner body.

5. Device as in any of the previous claims, wherein said inner body is at least partially threaded.

6. Device as in any of the previous claims, wherein said inner body is at one end provided with an impact cap (3).

7. Device as in any of the previous claims, wherein said outer body comprises a central guiding means (5) extending from said outer body towards said inner body and centred around said central longitudinal axis.

8. Device as in claim 7, whereby said central guiding means has a T-shaped outer end near said inner body.

9. Device as in any of the previous claims, wherein said housing is provided with a recess (17), wherein a screw (19) connected with said outer body is mounted to limit movement of the outer body.

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