SCREWDRIVER TOOLS AND ASSEMBLY METHOD WITH SCREWDRIVER TOOLS

Description

Technical area

[0001] The present disclosure relates to a screwing tool for transmitting torque to a screw. Furthermore, the present disclosure relates to an assembly method using a screwing tool, preferably this screwing tool. Background of the invention

[0002] To screw a screw into an internal thread, for example, to firmly connect two branches of a medical instrument to one another or, in particular, to connect them so that they can move relative to one another, for example, pivot, a torque must be applied to the screw. This torque can be transmitted to the screw, particularly by a screwing tool, in a form-fitting and / or force-fitting manner (i.e., frictionally engaged). The torque transmitted to the screw by the screwing tool must overcome the thread friction force acting between the screw and the internal thread.

[0003] Such a screwing tool is known, for example, from US 2009 / 0 229 846 A1. Furthermore, an assembly method for screwing in a screw is known, for example, from EP 2 873 381 A1.

[0004] For force-locking torque transmission, the screw is subjected to axial pressure / axial compressive force by the screwing tool, creating a surface friction force between the screwing tool and the screw. When the screwing tool rotates, a frictional torque resulting from the surface friction force is transferred to the screw. If the frictional torque between the screwing tool and the screw is smaller than the torque resulting from the thread friction force, the screwing tool slips and the screw is not screwed in. This can cause the screwing tool to slip, resulting in damage to a surface of the screw or a component with an internal thread.

[0005] The higher the axial pressure applied to the screw by the screwing tool, the greater the surface friction force and the resulting frictional torque that can be transmitted from the screwing tool to the screw. However, since the axial pressure applied to the screw also acts on the internal thread and thus the thread friction force increases with increasing axial pressure, the axial pressure cannot simply be increased arbitrarily to increase the torque that can be transmitted frictionally from the screwing tool to the screw. Summary of Revelation

[0006] This problem underlying the subject matter of the application is solved by the features specified in claims 1 and 9, and further embodiments are listed in the subclaims. Therefore, the object of the present disclosure is to provide a screwing tool with which a screw can be screwed in particularly easily and reliably. Furthermore, a suitable assembly method using a screwing tool, preferably this one, is to be provided.

[0007] The object of the present disclosure is achieved by a screwing tool having the features of patent claim 1 and by an assembly method having the features of the independent patent claim. Advantageous further developments are the subject of the dependent claims.

[0008] More specifically, the screwing tool has a first tool shank, preferably with a large shank diameter, and a second tool shank, preferably with a small shank diameter. The term "large" or "small" shank diameter refers to the shank diameter of the first tool shank being larger than the shank diameter of the second tool shank. Preferably, the large shank diameter approximately corresponds to the diameter of the screw head, while the small shank diameter preferably approximately corresponds to the diameter of a screw shank or the core diameter of the screw, or is smaller than the latter.

[0009] The first tool shank has an end-side screw engagement portion / screw head engagement portion, which is provided and configured to transmit a torque to a screw, in particular a screw head of the screw. Preferably, the end-side screw engagement portion / screw head engagement portion of the first tool shank can be rotatable and provided and configured to transmit a compressive force axially to the screw, in particular the screw head. As a result, the frictional torque (between the first tool shank and the screw) resulting from the compressive force upon rotation of the first tool shank can be transmitted from the first tool shank to the screw.

[0010] The second tool shank has an end-side screw engagement section / screw shank engagement section, which is provided and configured to transmit a compressive force axially to the screw, in particular to a screw end / screw shank end of the screw opposite the screw head. The second tool shank is orientable or oriented axially to the first tool shank and counter-axially to the first tool shank such that its end-side screw engagement section is axially opposite the end-side screw engagement section of the first tool shank and is provided and configured to transmit the compressive force axially to the screw in the direction toward the first tool shank.

[0011] In other words, the approximately punch-like first tool shank and the approximately punch-like second tool shank have a common longitudinal axis and are axially spaced from one another such that the screw engagement portion of the first tool shank faces the screw engagement portion of the second tool shank. Thus, the screw can be arranged in a longitudinally aligned manner between the first tool shank and the second tool shank. Furthermore, the second tool shank is displaceable along its longitudinal axis toward the first tool shank, so that the compressive force acting axially toward the first tool shank can be transferred to the screw, and thus from the screw to the first tool shank.Consequently, a force acting between the screw engagement portion of the first tool shank and the screw corresponds to a sum of the compressive force that can be applied by the first tool shank and the second tool shank in the direction of the opposite / counter-rotating tool shank.

[0012] The core of the disclosure is therefore that the screwing tool is provided and configured such that the screw can be clamped axially between the first tool shank and the second tool shank. This has the advantage that the axial pressure acting between the screwing tool and the screw can be increased while bypassing the internal thread (and avoiding a resulting increased thread friction torque). Simply put, the normal force acting on the surface of the screw, in particular the screw head, is increased, while the axial force acting on the screw (as a whole) in the direction of the second tool shank remains the same or is balanced by the compressive force of the second tool shank.

[0013] In other words, the screwdriving tool according to the disclosure has two separate tool shanks (co-axial) extending axially relative to one another (on a common axis), a common tool shank storage frame on which the tool shanks are held (preferably rotatably) and can be moved towards one another in the axial direction in order to clamp a screw axially between them (closed force flow via the tool shank storage frame, the two tool shanks and the screw clamped between them). The clamping force that can be applied axially to the tool shanks via the tool shank storage frame (by means of a pressure force device of the tool shank storage frame) is preferably adjustable (manually or automatically) (e.g. via a preload spring, hydraulic / pneumatic ram or a clamping screw) such that a pressure force is exerted between at least one tool shank (or the one on the screw head side) and the screw head side.its screw engagement section) and the screw, a frictional force is generated which enables the transmission of a specific screwing torque (from the screw head-side tool shank or both tool shanks) to the screw.

[0014] This has the advantage that the screw can be screwed in solely or at least predominantly by frictional force transmission with the screwing tool according to the application, thus creating freedom with regard to the design of the screw, in particular the shape of a screw head. In particular, the screw head can preferably be formed with a flat / unprofiled surface, so that essentially only frictional forces can act between the screw head and the screw engagement section of the tool shank on the screw head side (which is also preferably unprofiled / does not produce a positive connection). This avoids, in particular, disadvantages that arise due to an often angular outer or inner profile of the screw head, which is necessary for positive force transmission.Preferably, the screw head can be designed to be substantially rotationally symmetrical, thereby avoiding the formation of gaps, slits, pockets or the like, since tissue residues, dirt and body fluids cannot be reliably and completely removed from these when the instrument is reprocessed.

[0015] According to a preferred embodiment, the screw engagement portion of the first tool shank can have a substantially concavely curved, in particular spherical (smooth / unprofiled) or frustoconical surface. The screw engagement portion of the first tool shank can preferably be provided and designed such that the shape of the screw engagement portion substantially corresponds to the shape of the screw head. This means that the screw head preferably has a substantially convexly curved, in particular spherical (unprofiled) surface. Alternatively or additionally, the screw engagement portion of the second tool shank can have a substantially flat or concavely curved, in particular spherical (unprofiled) surface, according to a preferred embodiment.The screw engagement portion of the second tool shank can preferably be provided and configured such that the shape of the screw engagement portion corresponds to the shape of the screw end. This means that the screw end preferably has a substantially flat or convexly curved, in particular spherical, surface. As a result, the first tool shank and / or the second tool shank can be advantageously guided and centered. Thus, self-centering preferably occurs during assembly or during the clamping process of the screw between the axially spaced tool shanks.A further advantage of the soft-edged / curved surface design of the first tool shank and / or second tool shank is that damage caused by slipping of the screwing tool and thus any subsequent processing of the screw, which is necessary to ensure the surface quality required for medical, particularly surgical, instruments / devices, can be eliminated.

[0016] According to a preferred embodiment, the present disclosure relates to the screwing tool with a screw that is provided and configured to absorb the torque from the screw engagement portion of the first tool shank and the pressure force from the screw engagement portion of the second tool shank. In particular, the screw can have a substantially spherical (or spherical segment-shaped) screw head.

[0017] According to a preferred embodiment, the screwing tool can have a tightening device (section of the tool shaft storage rack / tool ​​shaft holding device for clamping a screw between the axially spaced tool shafts). The tightening device can preferably be provided and designed to adjust a rotation angle and / or the torque of the screw engagement section of the first tool shaft. Alternatively or additionally, the tightening device can preferably be provided and designed to measure a rotation angle and / or a torque of the screw engagement section of the second tool shaft. Thus, it is possible to adjust how far and / or how tightly the screw is screwed (into a medical instrument), i.e.which thread of the screw is engaged and / or the magnitude of the moment of resistance created by the screw connection, particularly between two components of a surgical instrument that are connected to each other in a movable / pivoting manner. This means that the tightening device can be used like a slip clutch to prevent overtightening of the screw being tightened.

[0018] According to a preferred embodiment, the screwing tool can have a (already indicated above) pressure force device (further section of the tool shank storage rack / tool ​​shank holding device). The pressure force device is preferably provided and designed to adjust, calculate, and / or measure the pressure force (from the second tool shank axially toward the first tool shank on the screw and / or from the first tool shank axially toward the second tool shank on the screw). In other words, the pressure force device is preferably provided and designed to adjust, calculate, and / or measure an axial clamping force of the screwing tool acting on the screw.In particular, the compression force device can be designed such that an axial distance between the first tool shank and the second tool shank can be changed / adjusted, for example by means of a threaded drive, for example, counteracting the restoring force of a spring. Thus, the axial clamping force / axial compression force can be determined depending on the length of the screw to be clamped in the screwing tool. The compression force device can be operated manually or, preferably, automatically.

[0019] According to a preferred embodiment, the first tool shank and the second tool shank can be mounted so as to be axially movable relative to one another, preferably axially displaceable or pivotable. Thus, the screw-engaging sections can be moved toward and away from one another in a simple manner, for example, like a press or pliers.

[0020] According to a preferred embodiment, the screw engagement portion of the first tool shank can be spring-loaded in the axial direction toward the second tool shank. Alternatively or additionally, the screw engagement portion of the second tool shank can be spring-loaded in the axial direction toward the first tool shank according to a preferred embodiment. This has the advantage that the spring preload allows a defined compressive force to be transmitted by the screw engagement portion, and thus also a defined tightening torque, to be set. Furthermore, damage to the screw caused by excessive compressive force can be avoided.

[0021] According to a preferred embodiment, the first tool shank can be integrally connected to the second tool shank so as to be rotatable about its longitudinal axis. This means that the second tool shank rotates along with the rotation of the first tool shank. Thus, a torque for screwing in the screw can also be transmitted from the screw-engaging portion of the second tool shank to the screw.

[0022] According to an alternative preferred embodiment, the first tool shank can be relatively rotatable about its longitudinal axis relative to the second tool shank. This means that the second tool shank remains stationary / does not rotate when the first tool shank rotates. Thus, the second tool shank serves only as a counter-holder for applying the axial compressive force. Alternatively, the second tool shank can be rotatable about its longitudinal axis independently of the first tool shank. Thus, a torque can also be applied to the screw via the second tool shank.

[0023] The object of the present disclosure is also achieved by an assembly method for screwing a screw into an internal thread of a medical instrument having two branches, preferably using a screwing tool as described, in order to connect the two branches with the screw in such a way that the two branches can be pivoted relative to each other around the screw as a hinge. The assembly method according to the application comprises the following steps: axially moving a first tool shank and a second tool shank of the screwing tool towards one another to clamp the screw between its screw head and its screw shank in the screwing tool, so that a compressive force is transmitted axially from the second tool shank in the direction of the first tool shank to the screw, rotating the screwing tool, in particular the first and optionally second tool shank, relative to the instrument about a longitudinal axis of the screw in order to transmit a torque (in particular for setting a tightening torque or a screw-in depth of the screw) to the screw clamped in the screwing tool and to screw the screw into the internal thread, and axially moving the first tool shank and the second tool shank apart to release the screw from the screwing tool.

[0024] In addition, a first branch of the two branches has a first through-hole, and a second branch of the two branches has a second through-hole, on which the internal thread is formed. According to a preferred embodiment of the assembly method, it comprises the following step: axially moving the second tool shank towards the first tool shank and through the second through-hole before the screw is clamped into the screwing tool and inserted into the internal thread, or passing the screw through the first through-hole and inserting the screw into the internal thread before the second tool shank is moved axially through the second through-hole towards the first tool shank and the screw is clamped into the screwing tool.

[0025] Accordingly, the screw can first be clamped into the screwing tool before it is inserted into the internal thread and screwed in, or the screw can first be inserted into the internal thread before it is clamped into the screwing tool and screwed in.

[0026] Preferably, the screw can be secured in its screwed-in position, for example by laser welding and / or by adhesive, which can be applied before clamping into the screwing tool.

[0027] In summary, a cleaning-optimized connecting element for surgical instruments is provided that solves the problem of tissue residue, dirt, and body fluids accumulating and adhering to the screw slot, which cannot be completely removed during the reprocessing process. Disadvantages of existing connecting elements include the fact that the sharp-edged slot base and slots cannot be reliably cleaned, and that assembly errors that are unavoidable in mass production, such as screwdriver slippage, require manual rework, for example, by polishing.The task therefore arises of enabling a combination of a fastener head design and a suitable assembly method in which there are no deep pockets, slots or the like with sharp edges at the base, and in which the applied tightening torques / assembly forces can be finely adjusted / dosed. The screw head and the threaded end can be spherical in design so that the spherical support guides the system and centers itself when the screw is tightened between its head and the threaded end during the assembly process. The force is transmitted via the friction force applied by a tool. The tightening torque or the thread pitch or the resistance moment of the moving parts can be finely adjusted and / or measured and / or recorded using a sensor. The screw connection can be secured in this screw position, if necessary, using adhesive, a laser weld spot or the like.Because the screw head is designed without a slot or similar force-transmitting element (positive locking device), the connecting element does not require post-processing to achieve the surface quality required for surgical instruments / devices. This results in process-reliable / reproducible machinability, simplified assembly by increasing the degree of mechanization during production, and improved cleaning properties. Short description of the characters

[0028] Figs. 1 to 4 show perspective views of a section of a screwing tool according to the application at different times of an assembly process carried out therewith, Figs. 5 to 7 show further perspective views of the screwing tool at different times during the assembly process carried out with it, Figs. 8 and 9show perspective views of a screw that can be screwed in with the screwing tool and an instrument into which the screw is screwed, and Figs. 10 to 12 show perspective views of the screwing tool with two axially extending tool shanks and a (screw clamp-like) tool shank storage / holding frame. Description of preferred embodiments

[0029] Hereinafter, preferred embodiments of the present disclosure will be described based on the accompanying figures.

[0030] Figs. 1 to 7show perspective views of a section of a screwing tool 1 according to the application at various times during an assembly process carried out therewith. The screwing tool 1 serves to screw a screw 2 having an external thread into an internal thread. In the illustrated embodiments, the internal thread is formed on a surgical instrument 3. In the illustrated embodiments, the screw 2 fixes two components of the instrument 3 in a manner that is movable, in particular pivotable, relative to one another.

[0031] The screwing tool 1 has a first tool shank 4 with a large shank diameter and a second tool shank 5 with a small shank diameter. The shank diameter of the first tool shank 4 is therefore larger than the shank diameter of the second tool shank 5. Preferably, the large shank diameter approximately corresponds to the diameter of a screw head 6 of the screw 2, while the small shank diameter preferably approximately corresponds to the diameter of a screw shank 7 or the core diameter of the screw 2 (or is slightly smaller).

[0032] The first tool shank 4 has a screw engagement section 8 at its end, which is provided and designed to transmit a torque to the screw 2, in particular the screw head 7. The screw engagement section 8 can preferably correspond to a shape of the screw head 7 and in particular have a concavely curved surface. The concavely curved surface can preferably be spherical, even if this is not explicitly shown in the figures. The second tool shank 5 is aligned axially to the first tool shank 4 and in the opposite direction to it. The first tool shank 4 and the second tool shank 5 therefore have a common longitudinal axis and are axially spaced from one another.The second tool shank 5 is oriented such that its end-side screw engagement section 9 is axially opposite the end-side screw engagement section 8 of the first tool shank 4 and is provided and designed to transmit a compressive force axially in the direction of the first tool shank 4 to the screw 2. This means that the screw 2 can be or is arranged axially between the first tool shank 4 and the second tool shank 5. The screw 2 can be clamped axially between the first tool shank 4 and the second tool shank 5. In the clamped state (cf. Figs. 1 to 4 ) the screw head 6 rests on the screw engagement section 8 and the screw shaft / a screw end 7 rests on the screw engagement section 9 of the screwing tool 1.

[0033] The first tool shank 4 and the second tool shank 5 can be mounted so as to be axially movable relative to one another, preferably axially displaceable or pivotable. For example, the first tool shank 4 and the second tool shank 5 can be designed in the manner of a press or in the manner of pliers.

[0034] Preferably, the screw engagement portion 8 of the first tool shank 4 can be spring-loaded in the axial direction toward the second tool shank 5, even if this is not shown. Preferably, the screw engagement portion 9 of the second tool shank 5 can be spring-loaded in the axial direction toward the first tool shank 4, even if this is not shown. For example, the first tool shank can be integrally connected to the second tool shank so as to be rotatable about its longitudinal axis, i.e., rotationally coupled. Alternatively, the first tool shank 4 can be relatively rotatable about its longitudinal axis relative to the second tool shank 5.

[0035] Fig. 5 shows the described cutting tool 1, in which the screw 2 is clamped between the two tool shafts 4, 5, without showing the instrument 3 into which the screw 2 is / should be screwed. Fig. 6 corresponds essentially Fig. 2 , in which a state during screwing in the screw 2 is shown, while Fig. 7 essentially Fig. 4 which shows a state with screw 2 screwed in.

[0036] Fig. 8 shows a perspective view of the screw 2 in a first preferred embodiment. The screw head 6 of the screw 2, or rather its surface, is convexly curved. In particular, the screw head 6 can be substantially rotationally symmetrical, for example, spherical. In this embodiment, the screw head 6 has no positive engagement surfaces.

[0037] Fig. 9shows a perspective view of the instrument 3 with the screw 2 screwed into it in the first preferred embodiment. The convex curvature and the circular shape of the screw head 6 prevent any gaps or pockets in which dirt, tissue residue, or fluids could collect.

[0038] Fig. 10 to 12show perspective views of the screwing tool 1. The screwing tool 1 can additionally have a pressure force device 10. The pressure force device 10 is provided and designed to set, calculate and / or measure the pressure force (from the second tool shank 5 axially in the direction towards the first tool shank 4 onto the screw 2 or from the first tool shank 4 axially in the direction towards the second tool shank 5 onto the screw 2). In other words, the pressure force device 10 is provided and designed to set, calculate and / or measure an axial clamping force of the screwing tool 1 acting on the screw 2. In particular, the pressure force device 10 is designed such that an axial distance between the first tool shank 4 and the second tool shank 5 is changeable / adjustable, for example by means of a screw drive.Thus, the axial clamping force / axial compressive force can be determined depending on the length of the screw 2 to be clamped in the screwing tool 1. The compressive force device 10 can preferably comprise a tension spring 11, against whose restoring force the axial distance between the first tool shank 4 and the second tool shank 5 can be changed—in the illustrated embodiment, reduced. The compressive force device 10 can be operated manually or, preferably, automatically.

[0039] The screwdriving tool 1 can additionally have a tightening device 12. The tightening device 12 is provided and designed to adjust and / or measure a rotation angle and / or the torque of the screw engagement section 8 of the first tool shank 4 and / or the screw engagement section 9 of the second tool shank 5. The tightening device 12 can be operated manually or, preferably, automatically. To adjust a defined screw-in depth of the screw 2, which is also referred to as setting a gear, and / or to adjust a defined tightening torque with which the screw 2 is screwed in, the torque transmitted by the screwdriving tool 1 to the screw 2, for example in the manner of a torque wrench, and / or the rotation angle transmitted by the screwdriving tool 1 to the screw 2, for example in the manner of an angle meter, can be adjusted and measured with the tightening device 12.This allows you to adjust how far the screw 2 is screwed in, ie which thread of the screw 2 is in thread engagement.

[0040] In the illustrated embodiment, the tightening device 12 has a first tightening wheel 13 which is connected in a rotationally fixed manner to the first tool shank 4. If the screw 2 is clamped in the screwing tool 1 and the first tightening wheel 13 is rotated relative to the instrument 3, the screw 2 is screwed into the instrument 3 with the frictional torque resulting from the axial compressive force. In the illustrated embodiment, the tightening device 12 has a second tightening wheel 14 which is connected in a rotationally fixed manner to the second tool shank 5. If the screw 2 is clamped in the screwing tool 1 and the second tightening wheel 14 is rotated relative to the instrument 3, the screw 2 is screwed into the instrument 3 with the frictional torque resulting from the axial compressive force. By rotating the two tightening wheels 13, 14, the maximum transferable frictional torque can be increased.The two tightening wheels 13, 14 can be rotatable / driven integrally with one another or can be rotatable / driven separately / individually from one another. Alternatively, only one tightening wheel can be provided, so that the first tool shaft 4, when rotated relative to the instrument, is also rotated relative to the second tool shaft 5 (and the second tool shaft 5 serves only as a counter-holder for applying the axial compressive force).

[0041] The screwdriving tool 1 can have a holder 15 to which the first tool shank 4 and / or the second tool shank 5 are attached. In the illustrated embodiment, the holder 15 has a first receptacle 16 on which the first tool shank 4 is rotatably mounted, and a second receptacle 17 on which the second tool shank 5 is rotatably mounted. The axial distance between the two receptacles 16, 17 can be adjusted via the pressure force device 10. The holder 15 has an axial guide 18, here in the form of two rods aligned parallel to the axis of rotation, by means of which an adjustment of the axial distance is predetermined in a guided manner parallel to the axis of rotation. A scale 19 is formed on the holder 15, which indicates a screwing-in or screwing-out direction (close or open) of the screwdriving tool 1.

[0042] As from Fig. 10As can be seen, the screwing tool 1 according to the application serves to screw the screw 2 into the internal thread of the instrument 3, which has two branches 20, 21, in order to connect the two branches 20, 21 of the instrument 3 to one another in such a way that the two branches 18, 19 can be pivoted relative to one another. The setting depth of the screw 2 or the thread of the screw 2 can be used to adjust the size of the section modulus created by the screw connection of the two branches 20, 21 of the instrument 3 that are thereby movably / pivotally connected to one another. Preferably, the first branch 20 of the two branches 20, 21 has a first through-hole. Preferably, the second branch 21 of the two branches 20, 21 has a second through-hole on which the internal thread is formed.In particular, the first through-hole is smaller than a diameter of the screw head 6, so that the two branches 20, 21 can be pivotally fixed to one another by the screw head 6 axially abutting the first through-hole, and the screw shaft 7 passing through the first through-hole and engaging the internal thread in the second through-hole.

[0043] The present disclosure also relates to an assembly method for screwing the screw 2 into the internal thread of the instrument 3 having the two branches 20, 21, in order to connect the two branches 20, 21 of the instrument 3 to one another such that they can be pivoted relative to one another. In one step of the assembly method, the first tool shank 4 and the second tool shank 5 are moved axially toward one another in order to clamp the screw 2 between its screw head 6 and its screw shank 7 in the screwing tool 1 such that a compressive force is transmitted axially from the second tool shank 5 in the direction of the first tool shank 4 to the screw 2 (and from the first tool shank 4 in the direction of the second tool shank to the screw 2). The screw engagement portion 8 of the first tool shank 4 is preferably moved such that it bears against the screw head over the entire surface of the screw head.The screw engagement portion 9 of the second tool shank 5 is preferably moved such that it bears against the screw shank 7 over an entire (axial) surface thereof.

[0044] In a subsequent step of the assembly method, the screwing tool 1, in particular the first tool shank 4 and preferably the second tool shank 5, is rotated relative to the instrument 3 about a longitudinal screw axis of the screw 2 in order to transmit a torque, in particular for adjusting a tightening torque or a screw-in depth of the screw 2, to the screw 2 clamped in the screwing tool 1 and to screw the screw 2 into the internal thread. If the screw 2 is clamped between the two screw engagement sections 8, 9, the torque can be frictionally transmitted to the screw 2 via the screw engagement section 8 of the first tool shank 4 by rotating the screw engagement section 8 of the first tool shank 4 about the longitudinal screw axis to generate a frictional torque.The screw engagement section 9 of the second tool shank 5 can rotate / be rotated to increase the frictional torque, or it can remain stationary (relative to the instrument 3) to apply the axial (counter) pressure force. In particular, the screwing tool 1 is moved in a helical manner to screw in the screw 2. Preferably, the screw 2 is screwed into the instrument 3 until the edge of the surface of the screw head 6 and / or the screw shank 7, depending on the instrument surface, is preferably completely, but at least partially, flush with a surface of the instrument 3.

[0045] In a subsequent step of the assembly process, the first tool shank 4 and the second tool shank 5 are moved axially apart in order to release the screw 2 from the screwing tool 1.

[0046] Preferably, the second tool shank 5 can be moved towards the first tool shank 4 and guided through the second through-hole (in the second branch 21 having the internal thread) before the screw 2 is clamped into the screwing tool 1 and inserted into the internal thread. The second tool shank 5 is therefore first guided through the instrument 3 ("from below", ie, an end of the instrument 3 opposite the screw head 6) before the screw 2 is clamped in the screwing tool 1, then inserted into the internal thread in the clamped state and screwed into the internal thread by torque transmission. In particular, the second through-hole is larger than the second tool shank 5 so that the second tool shank can be guided through the second through-hole from below to tighten the screw 2.

[0047] Alternatively, the screw can first be guided through the first through-hole in the first branch 20 and inserted into the internal thread in the second branch 21, before the second tool shank 5 is moved axially through the second through-hole toward the first tool shank 4 and the screw 2 is clamped into the screwing tool 1. Accordingly, the screw 2 is first inserted "from above," i.e., from an end of the instrument 3 near the screw head 6, into the internal thread, before the first tool shank 4 and the second tool shank 5 are moved toward each other to clamp the screw 2. In particular, the second through-hole is larger than the second tool shank 5 so that the second tool shank can be guided through the second through-hole from below to tighten the screw 2. The screw 2 can preferably be rotated about the screw's longitudinal direction, i.e.,For example, it can be screwed in manually a little / a few turns before screw 2 is clamped.

[0048] Preferably, the screw 2 can be secured in its screwed-in position by laser welding and / or by adhesive applied prior to clamping into the screwing tool 1. The scope of the invention is defined by the claims.

Claims

1. A screwdriving tool (1) for screwing a screw (2) in particular into an internal thread of a medical instrument (3), comprising - a first tool shaft (4) preferably having a large shaft diameter and an end-side screw engagement portion (8) which is provided and configured for transmitting a torque to the screw (2), - a second tool shaft (5) which preferably has a small shaft diameter and is orientable or oriented axially to the first tool shaft (4) and in the opposite direction thereto such that its end-side screw engagement portion (9) is axially opposite to the end-side screw engagement portion (8) of the first tool shaft (4), and is provided and configured to transmit a compression force axially to the screw (2) in the direction of the first tool shaft (4), and - a screw provided and configured to receive, from the screw engagement portion (8) of the first tool shaft (4), the torque and the compression force from the screw engagement portion (9) of the second tool shaft (5) and characterized in that the screw has a substantially spherical or frustoconical screw head.

2. The screwdriving tool (1) according to claim 1, characterized in that the screw engagement portion (8, 9) of the first tool shaft (4) and / or of the second tool shaft (5) have / has a concavely curved surface, in particular a substantially spherical or frustoconical surface.

3. The screwdriving tool (1) according to claim 1 or 2, characterized by a tightening device (12) provided and configured to set and / or measure a rotation angle and / or torque of the screw engagement portion (8, 9) of the first tool shaft (4) and / or of the second tool shaft (5).

4. The screwdriving tool (1) according to any of claims 1 to 3, characterized by a compression force device (10) which is provided and configured to set, calculate and / or measure the compression force.

5. The screwdriving tool (1) according to any of claims 1 to 4, characterized in that the first tool shaft (4) and the second tool shaft (5) are held axially movable, for example, axially pivotable or axially shiftable, relative to each other.

6. The screwdriving tool (1) according to any of claims 1 to 5, characterized in that the screw engagement portion (8) of the first tool shaft (4) is spring pre-tensioned in an axial direction toward the second tool shaft (5), and / or the screw engagement portion (9) of the second tool shaft (5) is spring pre-tensioned in the axial direction toward the first tool shaft (4).

7. The screwdriving tool (1) according to any of claims 1 to 6, characterized in that the first tool shaft (4) is integrally connected to the second tool shaft (5) in a rotationally coupled manner about its longitudinal axis.

8. The screwdriving tool (1) according to any of claims 1 to 6, characterized in that the first tool shaft (4) is relatively rotatable relative to the second tool shaft (5) about its longitudinal axis.

9. An assembly method for screwing a screw (2) into an internal thread of a medical instrument (3), using a screwdriving tool (1) according to any of claims 1 to 8, in order to connect two branches (20, 21) of the instrument (3) to each other such that the two branches (20, 21) are pivotable with respect to each other, characterized by the following steps: - axially moving a first tool shaft (4) and a second tool shaft (5) of the screwdriving tool (1) toward each other for clamping the screw (2) between its screw head (6) and its screw shaft (7) in the screwdriving tool (1), so that a compression force is transmitted axially from the second tool shaft (5) to the screw (2) in the direction toward the first tool shaft (4), - rotating the screwdriving tool (1), in particular the first tool shaft (4), relative to the instrument (3) about a longitudinal screw axis in order to transmit a torque, in particular for setting a tightening torque or a penetration depth of the screw (2), to the screw (2) clamped in the screwdriving tool (1), and to screw the screw (2) into the internal thread, and - axially moving the first tool shaft (4) and the second tool shaft (5) apart to unclamp the screw (2) from the screwdriving tool (1).

10. The assembly method of claim 9, wherein a first branch (20) of the two branches (20, 21) comprises a first through-hole and a second branch (21) of the two branches (20, 21) comprises a second through-hole in which the internal thread is formed, characterized by the following step: - axially moving the second tool shaft (5) toward the first tool shaft (4) and through the second through-hole before the screw (2) is clamped into the screwdriving tool (1) and inserted into the internal thread, or - passing the screw (2) through the first through-hole and inserting the screw (2) into the internal thread before moving the second tool shaft (5) axially through the second through-hole toward the first tool shaft (4) and clamping the screw (2) into the screwdriving tool (1).

11. The assembly method according to claim 9 or 10, in which the screw (2) is secured in its screwed-in position by laser welding and / or by adhesive applied before clamping in the screwdriving tool (1).