Medical hand-piece for the operation of treatment tools

Abstract

A medical, in particular dental, hand-piece (100) for the rotatable operation of treatment tools (150) has an arrangement (10) for clampingly holding the treatment tools (150), the arrangement (10) having a receiving sleeve (20) which is rotatable by a drive of the medical hand-piece (100), extends along an axis of rotation and has at least two first arms (25) which clampingly hold the treatment tool (150). Furthermore, a pressure piece (30) located downstream in the axial direction of the receiving sleeve (20) and movable relative to the receiving sleeve (20) in the axial direction is provided for releasing the treatment tool (150) from the clampingly holding arms (25), the pressure piece (30) having second clampingly holding arms (35) for holding the treatment tool (150).

Description

[0001] Medical handpiece for operating treatment instruments

[0002] The following invention relates to a medical handpiece for operating rotatable treatment tools, wherein the handpiece has an arrangement for clamping the treatment tool. In particular, the present invention relates to a dental handpiece, which is intended, for example, for operating a dental drill.

[0003] Dental treatments are still predominantly performed with handpieces that utilize a rotating bur to remove material from teeth or tooth surfaces. Both handpieces with a compressed air-driven turbine and those with an electric motor are known to power the bur. Regardless of the drive mechanism, these handpieces are designed so that the bur can be detached for replacement and separate cleaning.

[0004] Medical handpieces of the present type accordingly have a suitable arrangement for clamping the treatment instrument, which usually consists of several components. Figure 5 shows, in this context, a handpiece 100 known from the prior art, which has an elongated handle sleeve 110 with a head area 120 located at the front end, in which a corresponding arrangement for the releasable retention of a dental drill is provided.

[0005] A first component of this arrangement is a guide bushing or receiving sleeve 220, into which a shank section of the tool is inserted and positioned with minimal play, centered on a rotatably mounted axis. The guide bushing 220 is designed to absorb and counteract radial forces. To secure the tool axially, a clamping mechanism in the form of a collet 225 is also provided, into which the shank section of the tool is clamped by friction. This is intended to prevent as many axial and rotational movements as possible, so that the rotation generated by the drive is transmitted directly to the tool. Furthermore, by suppressing movement of the tool, potential damage during operation can be avoided.

[0006] To enable the tool to be released from the collet 225, a pressure piece 230, actuated by a push button 235, or a suitable opening mechanism is typically provided. This allows the collet 225 to be opened when the handpiece 100 is at rest, so that the tool can be removed with minimal effort. Such clamping systems are already known in many forms from the prior art and have proven their worth in practice.

[0007] However, with currently known clamping systems, it is not possible to completely prevent tool movement and thus tool wear within the tool holder. This is because the guide bushing or guide area into which the tool shank is inserted must always have at least a minimal amount of play relative to the shank to allow the tool to be inserted and removed from the clamping system. This play inevitably results in a certain degree of freedom for the held tool shank, which cannot be completely eliminated by the collet or the clamping mechanism in general. Particularly under higher forces during tool use, such as those that can occur when machining certain materials, the tool shank moves within these degrees of freedom, leading to the aforementioned undesirable wear.

[0008] The greatest degree of freedom for the tool is due to the aforementioned pressure piece, into which at least a portion of the tool shank also projects. Such pressure pieces must necessarily have a certain amount of play to allow actuation and thus deliberate release of the clamping mechanism. However, this creates the problem that the portion of the shank extending beyond the guide bushing and engaging with the pressure piece is not reliably and securely supported, leading to the problems mentioned above.

[0009] The present invention is therefore based on the objective of further developing known solutions for the clamping retention of treatment instruments in such a way that these instruments can be held more reliably and with less play in a medical handpiece. This objective is achieved by a medical handpiece having the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

[0010] The present invention reduces or eliminates the tool play typically present in the pressure piece, which is responsible for releasing the tool from the clamping holder of the collet. According to the present invention, the pressure piece can generate an additional clamping force to hold the tool, resulting in a significantly higher holding force overall. This allows the rotational movement of the drive to be transferred to the tool more efficiently, and reduces tool movement relative to the holding mechanism, thereby minimizing potential wear. In a particularly preferred embodiment, the holding force can be further increased when the tool is subjected to axial load during use.Ultimately, the solution according to the invention allows the tool to be clamped more centrally and securely into the receptacle of the treatment instrument.

[0011] According to the invention, a medical, in particular a dental, handpiece for the rotatable operation of treatment instruments is proposed, which has an arrangement for clamping the treatment instruments, wherein the arrangement comprises:

[0012] • a receiving sleeve rotatable by a drive of the medical handpiece, extending along an axis of rotation and having at least two first arms that clamp the treatment tool,

[0013] • a pressure piece arranged in the axial direction following the receiving sleeve and movable in the axial direction relative to the receiving sleeve for releasing the treatment tool from the clamping arms, wherein the pressure piece according to the invention has second clamping arms for holding the treatment tool.

[0014] According to the inventive solution, the pressure piece now assumes the function of an additional collet chuck, in addition to its original function, so that the tool is held clamped with greater force and over a larger axial range. Preferably, the second arms of the pressure piece are formed at its end region facing the receiving sleeve.

[0015] According to a particularly preferred embodiment, the pressure piece interacts with a guide element in such a way that, when the pressure piece is axially displaced away from the receiving sleeve, the clamping force exerted by the second arms of the pressure piece is increased, and when the pressure piece is axially displaced towards the receiving sleeve, the clamping force exerted by the second arms of the pressure piece is decreased. This constitutes a self-reinforcing system, which on the one hand optimizes the reliable retention of the treatment tool and on the other hand ensures that the tool can still be released in the usual manner using the pressure piece when it is to be removed from or taken off the handpiece.

[0016] Preferably, the pressure piece has a region on its outer circumference with an axially tapered outer circumference, which interacts with the axially fixed guide element surrounding the pressure piece, forming a guide surface that also tapers axially. In particular, the guide element can be formed by a conical ring with an axially tapered inner surface.

[0017] According to a first embodiment, the axially tapered outer circumference can be formed at the end region of the pressure piece facing the receiving sleeve. In this case, the arrangement preferably also includes a spring element which is supported on one side by the conical ring and on the other side by the pressure piece or a retaining ring fixedly arranged on the pressure piece. Preferably, the spring element and the retaining ring are designed as a single-piece component, and the conical ring can particularly preferably also be part of this single-piece component.

[0018] As an alternative to the variant just described, the axially tapered outer circumference can also be formed on a region of the pressure piece axially removed from the receiving sleeve. In this case, it is preferably provided that the arrangement for clamping the treatment tool further comprises a spring element which is supported on the pressure piece on one side and on the receiving sleeve on the other. The aforementioned spring element is preferably designed as a coil spring that surrounds the pressure piece in a ring-like fashion. It is particularly recommended that the coil spring be designed with at least two leads in order to minimize any imbalances as much as possible. The use of a disc spring would also be conceivable in principle.

[0019] As is already known from the prior art, the pressure piece can be designed to have at least two wedge-shaped spreading elements which engage in recesses separating the clamping arms of the receiving sleeve. The solution according to the invention allows the spreading elements to be designed with a relatively small wedge angle. In particular, this wedge angle can be less than 30°, preferably about 20°. This represents a further advantage over previous solutions, since a reduction in the wedge angle of the spreading elements reduces the force required to release the clamping mechanism when removing the tool. On the other hand, a reduced wedge angle generally carries the risk of the spreading element becoming jammed in the recesses between the clamping arms of the receiving sleeve.In the solution according to the invention, this danger is reduced or avoided by the effect of the additional spring, so that the reduced wedge angles, which are advantageous for handling, can be used here.

[0020] Preferably, the pressure piece also has a stop surface for the treatment tool at its end facing away from the receiving sleeve. If the treatment tool is subjected to axial load during treatment, this causes the pressure piece to be pushed away from the receiving sleeve in one direction, which, due to the aforementioned self-reinforcing mechanism, results in it being held even more firmly.

[0021] The various components of the tool holder according to the invention can be arranged in a carrier-supported bearing sleeve, which is coupled to the drive of the handpiece.

[0022] The invention will now be explained in more detail with reference to the accompanying drawing. Figure 1 shows a side view of a dental handpiece, which has an arrangement according to the invention for clamping a treatment instrument;

[0023] Figure 2 shows a sectional view of the arrangement according to the invention for holding the tool;

[0024] Figure 3 shows a view of the tool shank inserted into the arrangement according to the invention;

[0025] Figure 4 shows a sectional view of another variant of the arrangement according to the invention and

[0026] Figure 5 shows a sectional view of a dental handpiece which has a clamping mechanism known from the prior art for holding a tool.

[0027] Analogous to the dental handpiece known from the prior art and shown in Figure 5, the handpiece 100 according to the invention, shown in Figure 1, also initially has an elongated, slightly angled handle sleeve 110, at the front end of which a head section 120 is arranged. This serves to hold a dental treatment instrument 150, for example, a dental bur, which is rotated about an axis of rotation L for the purpose of ablation. The type of drive is not important for the present invention. It can be either a turbine handpiece, in which a turbine arranged in the head section 120 causes rotation of the instrument 150 by means of air pressure, or an electric motor handpiece, in which the rotation of a corresponding drive element caused by an electric motor is transmitted to the instrument 150.

[0028] In principle, however, it is intended that the tool 150 is detachably held in the head region 120 of the treatment instrument 100 in order to remove it and replace it with another tool if necessary. This requires the presence of a suitable clamping or holding mechanism that, on the one hand, ensures a reliable hold for the tool 150 and, on the other hand, allows the clamping hold to be released in order to free the tool 150. The measures provided for this purpose according to the invention will be explained in more detail below with reference to Figures 2 and 3.

[0029] The inventive arrangement for clamping the tool, shown in Figures 2 and 3 and generally designated by reference numeral 10, consists, like the prior art arrangement, primarily of a receiving sleeve 20 and a pressure piece 30. Both components are positioned one behind the other along the axis of rotation L and, in this case, are arranged in a bearing sleeve 60, which is rotatably mounted within the handpiece head 120 by means of bearings (not shown) and is set in rotation by the corresponding drive means. The receiving sleeve 20 serves to guide and clamp the shank 151 of the tool 150, which, as indicated by the arrow, is inserted into the receiving sleeve 20 from a receiving opening in the handpiece head 120.The inner diameter of the receiving sleeve 20 is dimensioned such that it corresponds as closely as possible to the diameter of the tool shank 151, whereby at least a minimal amount of play must necessarily be present to allow the insertion and removal of the shank 150.

[0030] A clamping hold for the tool 150 is achieved by dividing the receiving sleeve 20 into at least two first clamping arms 25 in an end region opposite the insertion opening by means of corresponding recesses or slots 26. In this region of the clamping arms 25, the inner diameter is slightly reduced, as can be seen in Figure 2, although the arms 25 can be deflected radially due to the slots 26. When the tool shank 151 is inserted, it displaces the two arms 25 slightly to the side, so that it can be inserted despite the reduced inner diameter. At the same time, the spring-like design of the arms 25 causes them to clamp against the outer circumference of the shank 151. Thus, at least over the axial region of the reduced inner diameter, the clamping arms 26 lie as flat as possible against the outer circumference of the tool 150 and hold it, as is already the case in the prior art.

[0031] Similarly to the prior art, the clamping holder of the tool 150 can be released by means of the arms 25 using the pressure piece 30, which has wedge-shaped spreading elements 36 corresponding to the recesses 26 and pointing towards the receiving sleeve 20. The pressure piece 30 is pre-tensioned in one direction away from the receiving sleeve 20, as described in more detail below, so that in the unactuated state the spreading elements 36 engage at least partially in the recesses 26 between the clamping arms 25 of the receiving sleeve 20, but do not yet deflect them laterally to release the clamping holder.Only when the pressure piece 30 is actuated, i.e., as in the prior art, by a push button 130 provided on the head area 120, is moved in the direction of the receiving sleeve 20, do the spreading elements 30, due to their wedge-like design, cause the clamping arms 25 to deflect laterally, thereby releasing the holder of the tool 150.

[0032] To allow relative movement of the pressure piece with respect to the receiving sleeve 20 and prevent it from being blocked by the tool shank 151, the pressure piece 30 must also have an axially extending cavity into which the tool shank 151 engages, as shown in Figure 3. This design is already known in the prior art, with the inner diameter of the receiving area of ​​the pressure piece 30 again being dimensioned such that minimal clearance exists for the tool shank 151.

[0033] However, a novel feature of the present invention is that, through a special design of the pressure piece 30, it is also used for clamping the tool shank 151. Analogous to the receiving sleeve 20, the wall area of ​​the pressure piece 30 is now also provided with elongated slots 34 such that arm segments or second clamping arms 35 are formed distributed around the circumference, which can be deflected radially or pressed inwards to a small extent. It is particularly preferred that the inner diameter of the receiving area of ​​the pressure piece 30 is initially selected such that, in the starting position, the arms 35 still have a certain amount of play relative to the outer circumference of the shank 151, allowing the shank to move freely along the axis L relative to the pressure piece 30.

[0034] However, as can be seen in Figure 2, the outer circumference of the pressure piece 30 is provided with a conically shaped surface 32 at its end region facing the receiving sleeve 20, in particular such that the outer circumference tapers in a direction away from the insertion opening. Similarly, a guide element 40 surrounding the pressure piece 30 is designed in the form of a conical ring with a conically tapered inner surface 41, which interacts with the outer circumference of the pressure piece 30 such that the second arms 35 are deflected towards the axis of rotation when the pressure piece 30 is moved in a direction away from the receiving sleeve 20.

[0035] Two different factors cause the pressure piece 30 to be displaced in the direction mentioned (i.e., to the right in Figure 2), thereby causing the wide arms 35 to exert an additional clamping force on the tool shank 151. i) Firstly, a spring 45 is provided, which acts between an end face of the conical ring 40 and a retaining ring 49, which is fixedly arranged on the outer circumference of the pressure piece 30. This spring 45, preferably designed as a reversible spring, surrounds the pressure piece 30 in a ring-like fashion and thus pushes the retaining ring 49 together with the pressure piece 30 in the corresponding direction. Alternatively, the retaining ring 49 could also be an integral part of the cylindrical surface of the pressure piece 30. The use of a disc spring instead of the reversible spring 45 shown would also be conceivable.ii) Secondly, the receiving area of ​​the pressure piece 30 facing away from the insertion opening is provided with a stop surface 37 against which the end face of the tool shank 151 comes into contact as soon as it has been inserted far enough or is axially loaded in the corresponding direction during the treatment.

[0036] Inserting the tool shank 151 into the receiving arrangement according to the invention causes the tool shank 151 to displace the pressure piece 30 at least slightly to the right as soon as it has been inserted sufficiently far. In this configuration, the end regions of the arms 35 of the pressure piece 30 are deflected towards the axis of rotation L due to the conical guide surfaces 32, 41 and exert a further holding force on the tool 100 in addition to the clamping arms 25 of the receiving sleeve 20. The tool 100 is thus held even more reliably and firmly compared to solutions known from the prior art, and this effect is further enhanced, as already mentioned, when the tool 150 is subjected to axial load during processing.

[0037] Conversely, if the tool 150 is to be removed, the pressure piece 30 is moved towards the receiving sleeve 20 against the force of the spring 45 using the push button 130. This causes the first clamping arms 25 of the receiving sleeve 20 to be deflected laterally by means of the wedge-shaped spreading elements 36. Simultaneously, the conical guide surfaces 32, 41 of the pressure piece 30 and the guide element 40 shift relative to each other in such a way that the retaining arms 35 can return to their initial position, and consequently, no clamping force is exerted on the shank section 151 of the tool 150. The tool can now be removed from the holder without significant effort.

[0038] Preferably, the guide element 40, the spring 45, and ideally also the retaining ring 49 can be designed as a single-piece component. The spring 45 ideally has at least two coils to avoid any imbalances.

[0039] A further particular advantage of using the spring 45 is that a force is exerted on the pressure piece 30 that points away from the receiving sleeve 20, thereby reducing the risk of the wedge-shaped spreading elements 36 jamming in the recesses 26 of the receiving sleeve 20. This, in turn, makes it possible to provide a relatively small wedge angle α for the spreading elements 36, in particular an angle of less than 30 degrees, preferably only about 20 degrees. Such a reduced angle has the advantage of reducing the force that must be exerted on the pressure piece 30 to release the jammed holder of the tool 150.At the same time, however, in solutions known from the prior art, such a small angle would entail an increased risk that the pressure piece 30 would jam with the receiving sleeve 20, as already mentioned, whereas this risk does not exist in the solution according to the invention due to the spring 45.

[0040] In the further embodiment shown in Figure 4, the axially tapered outer circumference 32 of the pressure piece 30 is formed on a region of the pressure piece 30 axially remote from the receiving sleeve 20. The arrangement of the ring-shaped guide element 40 with the conical inner surface 41 is also selected accordingly, so that it is located at the end of the bearing sleeve 60 furthest from the insertion opening for the tool. This also applies to the slots 34, through which the second arms 35 for clamping the tool shank are formed, which now extend in the direction of the push button (not shown).

[0041] In this case, the spring element 45 is located directly between the receiving sleeve 20 and the

[0042] Pressure piece 30 is effective. The reversible spring, which is again preferably used, is supported on one side by the annular end face of the receiving sleeve 20 and on the other side by an outwardly projecting projection 39 provided axially approximately in the middle of the pressure piece 30, so that the pressure piece 30 is pressed to the right by the spring 45 in the same way as in the previous embodiment. In this case as well, an additional clamping hold of the tool 150 can be achieved with the help of the pressure piece 30, which is further reinforced by the interaction of the two surfaces 32 and 41.

Claims

Claims 1. Medical, in particular dental, handpiece (100) for rotatable operation of treatment tools (150), comprising an arrangement (10) for clamping the treatment tools (150), wherein the arrangement (10) comprises: • a receiving sleeve (20) rotatable by a drive of the medical handpiece (100), which extends along an axis of rotation and has at least two first arms (25) that clamp the treatment tool (150), ♦ a pressure piece (30) arranged in the axial direction following the receiving sleeve (20) and movable in the axial direction relative to the receiving sleeve (20) for releasing the treatment tool (150) from the clamping arms (25), characterized in that the pressure piece (30) has second clamping arms (35) for holding the treatment tool (150).

2. Medical handpiece (100) according to claim 1, characterized in that the second arms (35) of the pressure piece (30) are formed at its end region facing the receiving sleeve (20) or at an end region of the pressure piece (30) away from the receiving sleeve (20).

3. Medical handpiece (100) according to claim 1 or 2, characterized in that the pressure piece (30) interacts with a guide element (40) such that when the pressure piece (30) is axially displaced away from the receiving sleeve (20), the clamping force exerted by the second arms (35) of the pressure piece (30) is increased, and when the pressure piece (30) is axially displaced towards the receiving sleeve (20), the clamping force exerted by the second arms (35) of the pressure piece (30) is decreased.

4. Medical handpiece (100) according to claim 3, characterized in that, that the pressure piece (30) has on its outer circumference a region (32) with an outer circumference that tapers in the axial direction, which interacts with the axially fixed guide element (40) surrounding the pressure piece (30), which forms a guide surface (41) that also tapers axially.

5. Medical handpiece (100) according to claim 4, characterized in that the guide element (40) is formed by a conical ring with an axially conically tapered inner surface.

6. Medical handpiece (100) according to claim 5, characterized in that the axially tapered outer circumference is formed at the end region of the pressure piece (30) facing the receiving sleeve (20).

7. Medical handpiece (100) according to claim 6, characterized in that the arrangement (10) for clamping the treatment tools (150) further comprises a spring element (45) which is supported on one side by the conical ring and on the other side by the pressure piece (30) or a fastening ring (49) attached to the pressure piece (30).

8. Medical handpiece (100) according to claim 7, characterized in that the spring element (45) and the retaining ring (49) are designed as a one-piece component, wherein preferably the conical ring is also part of this component.

9. Medical handpiece (100) according to one of claims 2 to 5, characterized in that the axially tapered outer circumference is formed on a region of the pressure piece (30) axially removed from the receiving sleeve (20).

10. Medical handpiece (100) according to claim 9, characterized in that, that the arrangement (10) for clamping the treatment tools (150) further comprises a spring element (45) which is supported on the one hand by the pressure piece (30) and on the other hand by the receiving sleeve (20).

11. Medical handpiece (100) according to one of claims 7, 8 or 10, characterized in that the spring element (45) is designed as a disc spring or as a reversible spring which surrounds the pressure piece (30) in a ring-like manner, wherein the reversible spring is preferably at least two-turn.

12. Medical handpiece (100) according to one of the preceding claims, characterized in that the pressure piece (30) has at least two wedge-shaped spreading elements (36) which engage in the clamping arms (25) of the receiving sleeve (20) by means of recesses (26) separating them from one another.

13. Medical handpiece (100) according to claim 12, characterized in that the spreading elements (36) have a wedge angle (a) of less than 30°, preferably about 20°.

14. Medical handpiece (100) according to one of the preceding claims, characterized in that the pressure piece (30) has a stop surface (37) for the treatment tool (150) at its end facing away from the receiving sleeve (20).

15. Medical handpiece (100) according to one of the preceding claims, characterized in that it has a rotatably mounted bearing sleeve (60) which is coupled to the drive, wherein the receiving sleeve (20) and the pressure piece (30) are received in the bearing sleeve (60).

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