Assembly method, screwdriver tool and screw kit

Abstract

The present disclosure relates to an assembly method for screwing a screw (2) into an internal thread of a medical instrument (3) using a screwdriver tool (1) for connecting two branches (13) of the instrument (3) to each other such that the two branches (13) are pivotable relative to each other, the method comprising the steps of impressing a punch shape (8) into a screw head (6) of the screw (2) by applying an axial compressive force to the screw (2) by said screwdriver tool (1) and rotating the screwdriver tool (1) about a longitudinal axis of the screw relative to the instrument (3) in order to transmit torque from the screwdriver tool (1) to the screw (2) in a positive locking manner via the impressing punch shape (9) and screw the screw (2) into the internal thread. The present disclosure further relates to a screwdriver tool (1) for carrying out the assembly method and a screw kit consisting of the screwdriver tool (1) and the screw (2).

Description

[Technical field]

[0001] The present disclosure relates to an assembly method for connecting two branches of a medical instrument such that the two branches are pivotable relative to each other, by means of a screwdriver tool, by means of screwing a screw into an internal thread of the instrument.Furthermore, the present disclosure relates to a screwdriver tool for carrying out such an assembly method, and to a screw kit including such a screwdriver tool and a screw. [Background technology]

[0002] In order to screw a screw into an internal thread, for example to connect two branches of a medical tool firmly to one another or in particular to allow them to move relative to one another, for example pivotally, it is necessary to apply a torque to the screw. This torque can be transferred to the screw with a form fit and / or a force fit (i.e. frictional engagement), in particular by means of a screwdriver tool. Such assembly methods for screwing in screws are known, for example, from DE 100 41 576 A1 or US 2005 / 135 898 A1. Alternatively, the two branches of the tool can also be connected by riveting, as known, for example, from DE 698 09 500T2.

[0003] When a screw is driven, the torque transmitted to the screw by the driving tool must overcome the thread friction forces acting between the screw and the female thread.

[0004] For press fit torque transmission, the thread is subjected to an axial pressure / compression force by the screwdriver tool to generate a surface friction force between the screwdriver tool and the thread, and when the screwdriver tool is rotated, the friction torque resulting from the surface friction force is transmitted to the thread. If the friction torque between the screwdriver tool and the thread is smaller than the torque resulting from the thread friction force, the screwdriver tool will slip and the thread will not be screwed in. This may cause the screwdriver tool to slip and damage the surface of the thread or the part with the female thread.

[0005] The higher the axial pressure applied to the thread by the driving tool, the greater the surface friction force and resulting friction torque that can be transferred from the driving tool to the thread. However, since the axial pressure applied to the thread also acts on the female thread, the thread friction force increases as the axial pressure increases, and it is not possible to simply increase the axial pressure to increase the friction torque that can be transferred from the driving tool to the thread in frictional engagement. Summary of the Invention

[0006] It is therefore an object of the present disclosure to provide a suitable assembly method that allows screws to be particularly easily and reliably screwed in. Furthermore, a screw driving tool for carrying out the assembly method and a screw kit including the screw driving tool and the screws are provided.

[0007] The object of the disclosure is solved by an assembly method having the features of claim 1 as well as by a screwdriving tool and a screw kit having the features of the independent claims. Advantageous further developments are the subject matter of the dependent claims.

[0008] More specifically, the assembly method serves to screw a screw into the female thread of the instrument using a screwdriver tool to connect two branches of the instrument to each other such that the two branches are pivotable relative to each other.

[0009] The assembly method comprises the steps of imprinting a punch shape into the preferably unprofiled head of the screw by applying an axial compressive force to the screw using the driving tool itself, and rotating the driving tool about a longitudinal thread axis relative to the instrument to transmit torque (in particular for setting the tightening torque or threading depth of the screw) from the driving tool to the screw in a form-fit manner (by frictional engagement) through the imprinted punch shape and drive the screw into the female thread.

[0010] Thus, the core of the present disclosure is that the screw head has, prior to assembly, preferably a non-engraved, i.e. smooth, e.g. flat or curved surface without form-fitting engagement surfaces. In particular, the screw head may be configured as a rotating body, i.e. a rotationally symmetric body that maps onto itself when rotated through any angle. During assembly, a punch shape is imprinted into the screw head, so that after assembly, the screw head has an engraved, i.e. relief-like, surface with recesses configured in the form of the punch shape that can act as form-fitting engagement surfaces when the screw is screwed in. When the screw driving tool is rotated, the punch shape of the screw driving tool engages with the imprinted punch shape, so that the torque from the screw driving tool to the screw is not only frictionally engaged (by application of a friction torque resulting from an axial compression force and frictional forces of the surfaces during rotation) but also by form-fitting to the screw.

[0011] This has the advantage that the maximum transferable torque from the driving tool to the screw can be increased. The punch shape is made, i.e. stamped, by the driving tool during assembly, so that the recess / impression on the screw head corresponds exactly to the punch shape / surface shape of the driving tool. This has the effect that the torque is transferred to the screw in a form-fitting manner, i.e. "slip-free" or "torque-loss-free", and the screw can be screwed into the female thread with a low torque applied by the driving tool.

[0012] According to a preferred embodiment, the assembly method may include the step of centering and aligning the driving tool and the screw when an axial compressive force is applied to the screw by the driving tool.

[0013] Centering alignment can ensure proper force transfer.

[0014] According to a preferred embodiment, the assembly method may include a step of axially moving a tool shaft of the screw driving tool and a counterhold tool to clamp the screw between its head and the screw shaft in the screw driving tool, a punch shape being imprinted on the screw driving tool by the clamping, and the screw driving tool with the screw clamped therein is rotated relative to the instrument to drive the screw.

[0015] This means that, according to a preferred embodiment of the assembly method, the screw can be axially clamped against the driving tool during assembly so that the axial pressure acting between the driving tool and the screw can be increased whilst bypassing the female thread (and thus avoiding an increase in thread friction torque).

[0016] In particular, the tool may be configured such that a first of the two branches comprises a first through hole and a second of the two branches comprises a second through hole in which an internal thread is arranged. According to a preferred embodiment, the assembly method may comprise the steps of: moving the counterhold tool axially towards the tool axis and passing it through the second through hole, after which the screw is clamped in the screw-driving tool and inserted into the internal thread, or moving the counterhold tool axially towards the tool axis through the second through hole and after which the screw is clamped in the screw-driving tool.

[0017] Thus, the screw can first be clamped in the driving tool and then it is inserted into the female thread and screwed in, or the screw can first be inserted into the female thread and then it is clamped in the driving tool and screwed in.

[0018] Preferably, the screw may be fixed in its screwed position, for example by laser welding and / or adhesive, which may be applied prior to clamping with the screw driving tool.

[0019] The object of the present disclosure is also solved by a screwing tool for carrying out the described assembly method, comprising a tool shank having an end-side thread engagement portion arranged and configured for transmitting torque to the thread, the tool having an engagement surface from which the punch shape protrudes, arranged and configured for imprinting a punch shape on the thread upon transmission of an axial compressive force towards the thread and for transmitting torque to the thread in the form of a form fit via the imprinted punch shape from the punch shape of the tool shank.

[0020] According to a preferred embodiment, the engagement surface of the tool shank may be concavely curved, in particular substantially spherical. Preferably, the engagement surface is smooth / without die-sinking other than the punched shape. The engagement surface of the tool shank may preferably be provided and configured such that its shape substantially corresponds to the shape of the screw head. This means that the screw head preferably has a substantially convexly curved surface, in particular a spherical surface (without die-sinking other than the stamped punch shape). This allows advantageous guiding and centering of the tool shank. Thus, preferably, self-centering is achieved during assembly or when applying an axial compression force from a screwdriver tool to the screw head.

[0021] According to a preferred embodiment, the punch shape may have rounded edges. This has the advantage of avoiding the formation of gaps, slits, pockets etc., from which tissue residues, dirt and body fluids cannot be reliably and completely removed when the instrument is reprocessed. A further advantage of the rounded / soft edge / curved design of the punch shape is that it avoids damage when the screwdriver tool slips off, and therefore avoids reworking of the threads, which is necessary to ensure the surface quality required for medical, especially surgical, instruments / devices.

[0022] According to a preferred embodiment, the screwdriving tool may have a counterhold tool which is axially oriented with respect to the tool shaft, or which is oriented opposite the tool shaft, such that its end thread engagement portion is axially opposite the end thread engagement portion of the tool shaft, and which is arranged to transmit an axial compression force to the thread in the direction towards the tool shaft. In other words, in addition to the substantially punch-shaped tool shaft, the substantially punch-shaped counterhold tool may have a common longitudinal axis and be arranged axially spaced apart from each other, such that the thread engagement portion of the tool shaft faces the thread engagement portion of the counterhold tool. The thread can thus be arranged in longitudinal alignment between the tool shaft and the counterhold tool. Furthermore, the counterhold tool is displaceable along its longitudinal axis towards the tool shaft, so that a compression force acting axially towards the tool shaft can be transmitted to the thread and thus from the thread to the tool shaft. As a result, the force acting between the thread engagement portion of the tool shaft and the thread corresponds to the sum of the compression forces which can be applied by the tool shaft and the counterhold tool in the direction of the opposite / opposite tool shaft or counterhold tool, respectively. The thread can thus be clamped axially between the tool shaft and the counterhold tool. This has the advantage that the axial pressure acting between the screwdriver tool and the thread can be increased whilst bypassing the female thread (and thus avoiding increased thread friction torque). In simple terms, the normal force acting on the surface of the thread, and in particular on the head, increases, whilst the axial force acting on the thread (as a whole) in the direction of the counterhold tool remains unchanged or is compensated for by the compressive force of the counterhold tool.

[0023] According to a preferred embodiment, the punch shape can have the form of a quality mark, for example constructed as a letter, so that the user can recognize that the assembly has been carried out in an application-specific manner and that the screws have been tightened to the required torque.

[0024] The present disclosure also relates to a screw kit comprising the described screw driving tool and a screw having a screw head, the surface of which is preferably free of engraving and serves as an imprinting surface for imprinting a punch shape. According to a preferred embodiment, the screw head may have a convex, preferably substantially spherical, shape. In particular, the screw head may be configured as a revolutionary body, i.e. a rotationally symmetrical body which maps onto itself when rotated through any angle.

[0025] In other words, the assembly method according to the present application can provide a connecting element for surgical instruments optimized for cleaning, which solves the problem that tissue residues, dirt and body fluids collect and adhere in the slits of the screw or around the screw head and are not completely removed during the reprocessing process. The disadvantages of conventional connecting elements include the inability to reliably clean the sharp-angled slit bases and gaps, and the need to manually rework assembly errors that are unavoidable in mass production, such as screwdriver slippage, for example by grinding. The aim is therefore to enable the combination of a design of a connecting element head and a suitable assembly method that does not have deep pockets, slits, etc. with sharp angles at the bottom, but at the same time the holding force of the fixed connection is the same or even higher than before and the applied tightening torque / assembly force can be finely adjusted / given. Here, the screw head and the thread end can be spherical, so that during the assembly process, when the screw is clamped between its head and the thread end, or when a screwdriver tool is pressed into the screw with an axial compression force, the spherical support guides and self-centers the system. During the clamping process, a predetermined shape is imprinted at the contact points of the screw, which is used for the force transmission of the form-fit and force-fit. During this process, the tightening torque or the action or section modulus of the moving parts can be fine-tuned and / or measured and / or recorded by a sensor system. If necessary, the screw connection can be fixed in this screw position via adhesive, laser weld spots, etc. Since the screw head is designed without slits or similar force transmission elements (form-fit means) before assembly, there is no need to rework the connection elements to achieve the required surface quality of the surgical instrument / device. In summary, this results in higher mechanical strength, reliable / reproducible machinability of the process, simplified assembly due to a higher degree of mechanization during production, and good cleanability. [Brief description of the drawings]

[0026] [Figure 1] 1 shows a perspective view of a part of a screwdriver tool according to the present application, which is provided for carrying out the assembly method according to the present application; [Diagram 2]1 shows a perspective view of a screw that can be screwed in using a screwdriver tool before assembly and an instrument into which the screw is screwed in using the assembly method according to the present application. [Diagram 3] 1 shows a perspective view of a screw that can be screwed in using a screwdriver tool before assembly and an instrument into which the screw is screwed in using the assembly method according to the present application. [Figure 4] 4A-4D show further perspective views of the driving tool at different times during the assembly carried out with the tool; [Diagram 5] 4A-4D show further perspective views of the driving tool at different times during the assembly carried out with the tool; [Figure 6] 4A-4D show further perspective views of the driving tool at different times during the assembly carried out with the tool; [Figure 7] 1 shows a perspective view of a preferred embodiment of a driving tool according to the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Preferred embodiments of the present disclosure will now be described with reference to the accompanying drawings.

[0028] 1 shows a perspective view of a particular section of a screwdriving tool 1 according to the present application. The screwdriving tool 1 is used to screw a screw 2 having an external thread into an internal thread, which in the embodiment shown is constituted by a surgical instrument 3. In the embodiment shown, the screw 2 fixes two components of the instrument 3 in such a way that they are movable, in particular pivotable, relative to one another.

[0029] The screw driving tool 1 comprises a tool shank 4 including an end thread engaging portion 5 arranged for transmitting torque to the screw 2 , in particular to the head 6 of the screw 2 .

[0030] The thread engaging portion 5 of the tool shaft 4 has an engaging surface 7 from which a punch shape 8 protrudes, configured and arranged to stamp a punch shape 8 into the thread 2 (to form an stamped punch shape 9) upon transmission of an axial compressive force towards the thread 2 and to transmit torque from the punch shape 8 of the tool shaft 4 to the thread 2 with a (frictional and) form fit via the stamped punch shape 9.

[0031] The engagement surface 7 may preferably correspond to the shape of the screw head 6, in particular may be concavely curved. Preferably, the engagement surface 7 may be spherical (or rounded). Preferably, the engagement surface 7 is smooth / free of die-sinking except for the punch shape 8.

[0032] Preferably, the punch shape 8 (and therefore also the engraved punch shape 9) may have rounded edges. The punch shape 8 may be in the form of a quality symbol, for example configured as a letter. In the illustrated embodiment, the punch shape 8 has the shape of an "A".

[0033] 2 shows a screw 2 that can be screwed into a tool 3 using the assembly method according to the present application before assembly. In particular, the screw head 6 may have a non-engraved, i.e. smooth, e.g. flat or curved, surface 10 without form-fitting engagement surfaces before assembly. The surface 10 serves as an imprinting surface for imprinting the punch shape 8. In the illustrated embodiment, the screw head 6 is configured as a revolutionary body, i.e. a rotationally symmetrical body that maps onto itself when rotated through any angle. In the illustrated embodiment, the surface 10 of the screw head 6 is convexly curved.

[0034] During assembly, the punch feature 8 is stamped into the screw head 6 (i.e. into a surface 10 of the screw head 6), so that after assembly (see FIG. 3 ), the screw head 6 has a engraved or relief-like surface 11 configured with recesses in the form of the punch feature 8, i.e. the stamped punch feature 9, which can serve as a form-fit engagement surface when screwing in. When the driving tool 1 is rotated, the punch feature 8 of the driving tool 1 engages into the stamped punch feature 9, so that torque from the driving tool 1 to the screw 2 can be transmitted not only by frictional engagement, but also by form fit to the screw 2.

[0035] Preferably, the screw-driving tool 1 may comprise a counterhold tool 12 which can or is axially oriented with respect to the tool shaft 4, opposite the tool shaft 4, with its end thread-engaging portion axially facing the end thread-engaging portion 5 of the tool shaft 4, and which is arranged to transmit an axial compressive force to the screw 2 in the direction towards the tool shaft 4 (see Figures 4 to 6). This allows the screw 2 to be clamped by the screw-driving tool 1 in order to stamp the punch profile 8 and transmit torque from the screw-driving tool 1 to the screw 2 by form-fit and frictional engagement.

[0036] The present disclosure further relates to an assembly method of threading a screw 2 into an internal thread of the instrument 3 to connect two branches 13 of the medical instrument 3 such that the two branches 13 are pivotable relative to one another. The medical instrument 3 and a preferred embodiment are shown in more detail in FIG. 7 and described below.

[0037] In one step of the assembly method, a punch profile 8 is stamped into the preferably non-embossed head 6 of the screw 2 (see FIG. 2) by applying an axial compressive force to the screw 2 using the driving tool 1 itself. In this process, a surface 10 of the head 6, which is non-embossed before assembly, serves as the striking surface. In a later step of the assembly method, the driving tool 1 is rotated about its longitudinal thread axis relative to the instrument 3 in order to transfer torque (in particular for setting the tightening torque or the threading depth of the screw) from the driving tool 1 to the screw 2 in a form-fit via the stamped punch profile 9 and to screw the screw 2 into the female thread (see FIG. 3).

[0038] Preferably, the driving tool 1 and the screw 2 can be placed in a central position when an axial compressive force is applied to the screw 2 by the driving tool 1. This centered alignment is achieved in particular via the concave engagement surface 8 and the convexly configured non-embossed surface 10 of the screw head 6.

[0039] Preferably, the driving tool comprises a counterhold tool 12 (see Figures 4 to 6). In particular, the tool shaft 4 of the driving tool 1 and the counterhold tool 12 can be moved towards each other in order to clamp between the head 6 and the shaft of the screw 2 in the driving tool 1. In this process, the punch shape 8 is imprinted on the driving tool 1 by clamping, and the driving tool 1 is rotated relative to the instrument 3 in order to screw in the screw 2 with the screw 2 clamped therein.

[0040] In particular, the instrument 3 can be configured such that a first of the two branches 13 has a first through hole and a second of the two branches 13 has a second through hole in which an internal thread is configured. For example, the counterhold tool 12 can be moved through the second through hole towards the tool axis 4, after which the screw 2 is clamped in the screw-driving tool 1 and inserted into the internal thread. Alternatively, the screw 2 can be inserted through the first through hole into the internal thread, after which the counterhold tool 12 is moved axially through the second through hole towards the tool axis 4 and the screw 2 is clamped in the screw-driving tool 1.

[0041] Preferably, the screw 2 can be fixed in its screwed-in position, for example by laser welding and / or by adhesive, which can be applied before clamping with the screwdriving tool 1 .

[0042] Figure 7 shows a preferred embodiment of a screwdriver tool 1, which comprises a tool shaft 4 and a counterhold tool 12. Furthermore, Figure 7 shows the branches 13 of an instrument 3, which are connected to one another by the assembly method according to the present application via a screw 2 in such a way that the two branches 13 are pivotable relative to one another.

[0043] The driving tool 1 may have a holder 14 in which the tool shank 4 and / or the counterhold tool 12 are mounted. In the illustrated embodiment, the holder 14 has a first receptacle in which the tool shank 4 is rotatably mounted and a second receptacle in which the counterhold tool 12 is rotatably mounted.

[0044] The screwdriving tool 1 may further comprise a compression force device 15, which is provided and configured to set, calculate and / or measure a compression force (axially from the counterhold tool 12 towards the tool axis 4 on the screw 2 or from the tool axis 4 towards the counterhold tool 12 on the screw 2). The axial distance between the two receptacles is adjustable via the compression force device 15. The holder 14 has axial guides 16, in this case in the form of two rods aligned parallel to the axis of rotation, by which the adjustment of the axial distance parallel to the axis of rotation is guided. A scale 17 is provided on the holder 14, which indicates the closing or opening direction of the screwdriving tool 1.

[0045] The screwdriving tool 1 may further comprise a clamping device 18 arranged and configured to adjust and / or measure the rotation angle and / or torque of the tool shaft 4 and / or the counterhold tool 12. The clamping device 18 can be operated manually or preferably automatically. The clamping device 18 can be configured in the form of a clamping wheel connected to the tool shaft 4 in a rotatably fixed manner or a clamping wheel connected to the counterhold tool 12 in a rotatably fixed manner.

Claims

1. 1. An assembly method for connecting two branches of a medical instrument to each other such that the two branches are pivotable relative to each other, comprising the steps of: imprinting a punch shape into the head of the screw by applying an axial compressive force to the screw using the screw driving tool itself; rotating the driving tool about a longitudinal thread axis relative to the instrument to transmit torque from the driving tool to the screw in a form-fit manner via the impressed punch feature and drive the screw into the female thread; The assembly method comprises:

2. 2. The method of assembly of claim 1, including the step of centering alignment of said driving tool with said screw when said axial compressive force is applied to said screw by said driving tool.

3. axially moving a tool shank of the screw driving tool and a counterhold tool to clamp the screw in the screw driving tool; the punch shape is imprinted on the driving tool by the clamping; 3. The method of claim 1 or 2, wherein the driving tool with the screw clamped therein is rotated relative to the instrument to drive the screw.

4. A first branch of the two branches includes a first through hole; A second branch of the two branches includes a second through hole in which the female thread is formed, or, moving the counterhold tool axially toward the tool axis and through the second through hole, and then clamping the screw in the screw driving tool and inserting it into the female thread; or 4. The assembly method according to claim 3, further comprising the step of passing the screw through the first through hole, inserting the screw into the female thread, and then axially moving the counterhold tool through the second through hole toward the tool axis to clamp the screw with the screw driving tool.

5. A screwdriver for carrying out the assembly method according to claim 1, comprising: a tool shaft having an end thread engaging portion configured to transmit torque to the thread; The thread engagement portion of the tool shank has an engagement surface from which a punch shape protrudes, the engagement surface being configured to imprint a punch shape on the thread when an axial compressive force is transmitted toward the thread, and to transmit torque to the thread by form-fitting from the punch shape of the tool shank via the imprinted punch shape.

6. A driving tool according to claim 5, characterized in that the engagement surface is concavely curved, in particular substantially spherical.

7. A screwdriver tool according to claim 5 or 6, characterized in that the punch shape has rounded edges.

8. 7. The screw driving tool according to claim 5 or 6, characterized in that the screw driving tool comprises a counterhold tool which is orientable or oriented axially opposite the tool shaft such that an end thread engaging portion of the counterhold tool is axially opposed to the end thread engaging portion of the tool shaft and which is adapted to transmit an axial compressive force to the screw in a direction towards the tool shaft.

9. 7. A screwdriver tool according to claim 5 or 6, characterized in that the punch shape has the form of a quality mark, for example in the form of a letter.

10. 7. A screw kit comprising the screw driving tool according to claim 5 or 6 and a screw having a screw head, the surface of the screw head being preferably not engraved and serving as an imprinting surface for imprinting the punch shape.

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