EP1887962A1

EP1887962A1 - Handpiece with coating for moved or movable parts

Info

Publication number: EP1887962A1
Application number: EP06742967A
Authority: EP
Inventors: Rainer Hofer
Original assignee: Kaltenbach and Voigt GmbH
Current assignee: Kaltenbach and Voigt GmbH
Priority date: 2005-05-30
Filing date: 2006-05-17
Publication date: 2008-02-20
Also published as: EP1728483A1; WO2006128587A1; US20080213722A1

Abstract

In a handpiece (100, 101) which is provided in particular for medical or dental purposes, and which has a drive mechanism for a tool (12, 105) to be held by the handpiece (100, 101), moved or movable parts of the handpiece (100, 101) are provided at least partially with a coating that contains chromium nitride and/or titanium nitride + gold.

Description

Handpiece with coating for moving or moving parts

The present invention relates to a handpiece according to the preamble of claim 1, which has a drive mechanism for a tool to be held by the handpiece, wherein moving or movable parts of the handpiece are at least partially provided with a coating. In particular, the present invention relates to a handpiece which is intended for medical, dental or dental technical purposes.

Dental or dental handpieces exist in various embodiments. The handpieces can be distinguished both by their shape and arrangement of the tools to be operated as well as in terms of the drive mechanism used for use. Thus, on the one hand, it is possible to arrange the tool at an angle of approximately 90 ° to the longitudinal axis of the handpiece, such configurations being used, for example, in dental drills for lifting off tooth substance. In dental technology, on the other hand, handpieces are often used for the production of dental prostheses, in which the tool is arranged in the direction of the longitudinal axis of the handpiece.

If the tool is to be rotated by means of the drive mechanism, essentially two different drive principles are used in dentistry or dental technology. On the one hand, air turbines are frequently used in which a rotor arranged in the head region of the handpiece is set in rotation by means of compressed air, on the other hand electric drives are also used, which bring advantages in particular if precise control of the rotational speed and of the tool applied torque is desired. Furthermore, however, there are also pneumatic drives, which are used, for example, when the tool is not to be set in rotation, but in an oscillating motion.

All different embodiments of dental or dental handpieces have in common that the moving or moving parts located therein are exposed to a relatively high load. It should also be noted that these are mainly miniaturized components, since the cramped space within the handpieces use large-volume Do not allow components. However, the smaller the components used, the more difficult it is for them to bear the loads occurring during operation or use of the handpiece. Components that are subjected to a particularly high load, for example, all components of the drive mechanism, which are responsible for transmitting a rotation to the tool or generally for a movement of the tool.

Another area of a dental handpiece that is subject to a relatively high load and thus the risk of wear is the head area within which the tool is located. Usually handpieces are designed so that a simple change of tools is possible. This is necessary for the sole reason that the tools also wear out over time as well as have to be cleaned and sterilized for hygienic reasons. Accordingly, so-called tensioning devices are used, which hold the tool securely and firmly during operation, and then allow removal of the tool. The components of such a clamping device are exposed to a high load, as for the firm and secure holding of the tool within the clamping device, a high power transmission is required.

In order to reduce the wear of the various components of a clamping device, it is proposed in WO 03/071973 Al to provide the components of a clamping device of a dental handpiece with a coating comprising graphite or chromium nitrate. In the case of the graphite-containing coating, reference is made in particular to so-called diamond-like or diamond-like hard material layers (diamond-like carbon DLC), which have a high hardness and, in addition, also improve the friction properties due to the amorphous carbon. Another feature of the coatings described in WO 03/071973 A1 is that they counteract corrosion of the components of the clamping device.

The coating of certain components of a dental handpiece is also described in WO 2004/056280 A1. In this case, however, care is taken in the first place that the coating leads to a reduction of the friction and accordingly can be dispensed with an excessive lubrication of the various handpiece components. Accordingly, it is proposed in WO 2004/056280 Al to provide mutually moving parts of a dental handpiece with a coating which has a lubricant. As a particularly preferred embodiment, in turn, the use of diamond-like carbon layers DLC is called.

Based on the above-described prior art, the present invention seeks to provide a novel designed handpiece especially for medical, dental or dental technology purposes, which has further improved properties in terms of its moving or moving parts.

The object is achieved by a handpiece, which has the features of claim 1. Advantageous developments of the invention are the subject of the dependent claims.

The central idea of the present invention is to provide moving or movable parts of the handpiece with a coating comprising chromium nitride (CrN) and / or titanium.

Nitride + gold (TiN + Au) to further improve their operating characteristics. In contrast to the prior art, which suggests the use of diamond-like coatings or chromium nitrate layers, according to the present invention, therefore, a novel coating is used, since experiments have shown that chromium nitride or the combination of titanium nitride + gold compared to the The above-mentioned coatings bring further improved properties, in particular with regard to use in the dental or dental technology sector. Further advantages result from the fact that the coating of the components with chromium nitride or titanium nitride + gold can be carried out with a very high accuracy and, in particular, reliably and reproducibly.

According to the present invention, therefore, a handpiece is proposed with a drive mechanism for a tool to be held by the handpiece, in particular for medical, dental or dental technology purposes, wherein moving or movable parts of the handpiece are at least partially provided with a coating and according to the invention, the coating comprises chromium nitride and / or titanium nitride + gold.

In a first particularly preferred embodiment of the present invention, the handpiece on a clamping device for selectively clamping a to be moved by the drive mechanism, in particular to be set in rotation tool, wherein elements of this clamping device with the provided according to the invention used chromium nitride coating or titanium nitride + gold coating. A second preferred embodiment of the present invention is to use a drive mechanism for the tool, which has at least one driven and rotatably mounted shaft, wherein bearing elements for the shaft and / or coupling parts for rotation transmission are provided with the coating according to the invention.

These are two particularly preferred regions or components of the handpiece in which the chromium nitride coating or titanium nitride + gold coating according to the invention is to be used. Of course, however, all components of the handpiece, which are subject to wear, can be provided with the coating. The chromium nitride or titanium nitride + gold coating is therefore very versatile and contributes in all areas to improve the operating characteristics of the coated components and thus the handpiece as a whole.

The present invention is by no means limited to the use of specially designed handpieces. Rather, the chromium nitride or titanium nitride + gold coating can be used in all handpieces that are used in medical, dental or dental technology areas. The operating characteristics of both dental drill handpieces and straight motor handpieces for the laboratory can be further optimized in this way.

The invention will be explained in more detail with reference to the accompanying drawings. Show it:

Fig. 1 shows a first embodiment in game of a dental according to the invention

Handpiece in side view;

Figure 2 shows the head portion of the handpiece of Figure 1 in vertical section. and

3 and 4 show another embodiment of a straight motor handpiece, which is designed according to the present invention.

Two different handpieces are explained below, which are intended for use in the dental or dental technology area and are designed according to the teaching of the present invention. This is on the one hand a Bohrhandstück and on the other hand a straight Motor handpiece. It should, however, be pointed out again at this juncture that the use according to the present invention of the chromium nitride or titanium nitride + gold coating can be used in all medical, dental or dental handpieces.

In the embodiment shown in FIGS. 1 and 2 is a handpiece, which is known from DE 196 29 902 Al the applicant. Since the design of this handpiece is already adequately described in this publication, its structure will be explained below only briefly.

The main parts of the handpiece 100 shown in FIGS. 1 and 2 are a grip sleeve 1 with a head housing 2 at its front end, a drive shaft section comprising two drive shafts 3, which is rotatably mounted in the grip sleeve 1 by means of corresponding bearings 3b, a drive sleeve 4 which by means of rotary bearings 5 about a rotation axis 6 rotatably mounted in the head housing 2, wherein the axis of rotation 6 preferably perpendicular to the longitudinal central axis 7 of the grip sleeve 1 extends, a drive connection between the drive shaft portion and the drive sleeve 4, here in the form of an angular gear 8 with corresponding pinions, a first clutch 9, for releasably rotational drive connection of a plug-in externally in the drive sleeve 4 shaft 11 of a rotary tool 12, a second clutch 13 for releasable axial connection of the shaft 11 with the drive sleeve 4 and an actuator 14 for releasing the second clutch 13 for the purpose of removing the Tool 12 from the handpiece 100th

The grip sleeve 1 is connectable by a plug connection 15 to a fitting 17 of a flexible supply line 18, the other end of which is connected to a supply device, not shown, for supplying the handpiece with required media, such as e.g. electrical drive power, blowing air, water and / or spray is connected. For this serve so-called. Media lines 16, which can extend longitudinally through the supply line 18 and the connector 15, as it is known per se. The water and / or air and light media conduits terminate in or near the head housing 2, with their exit ports directed toward the treatment site located at the tip of the tool 12.

An electric drive motor 19 is arranged in a manner known per se in the connection piece 17. With the aid of the motor 19, the tool 12 is set in rotation, whereby the transmission of the motor movement to the tool 12 via the two shafts 3, located on the shafts 3 coupling elements 3a and the angle gear 8 takes place. The first coupling 9 in the head housing 2 is formed by an inner projection 21 in the drive sleeve 4 with a coupling surface 22 which rests against a coupling surface 23 of the shaft 11 with little play, the coupling surface 22 by an end expiring recess or flattening of the shaft 11th is formed. The inner projection 21 is formed by a circular portion-shaped coupling part which is inserted as a fitting in a groove N.

The second clutch 13 for axially effective connection of the shaft 11 with the drive sleeve 4 is by a coupling slide 24 which is radially slidably mounted in a radial guide slot of the drive sleeve 4 with little play, as well as at its radially inner end a coupling nose 25, and a the latter receiving coupling recess 26 formed in the shaft 11.

The coupling slide 24 is between a coupling position shown in FIG. 2, in which its inward movement is limited by a stop A and in which the coupling nose 25 protrudes into the hollow cylindrical insertion hole 4a of the drive sleeve 4 and a displaced to the outside decoupling position or release position displaceable, in the coupling nose 25 does not protrude into the insertion hole 4a. For automatic return of the coupling slide 24 in its coupling position a spring 37 acting radially inwardly is provided. The spring 37 is elastically opened when moving the coupling slide 24 in its release position, which allows their clasp-shaped or C-shape. Due to the elastic contraction, the coupling piece 24 is automatically moved into its coupling position.

To release the second clutch 13, the actuating device 14 is provided, which is arranged on the side facing away from the tool 12 of the head housing 2 or accessible from this side. It has a pressure member 46, which is manually displaceable in a guide 47 axially between an inwardly shifted functional position and an outwardly shifted ready position.

To open the clutch 13, the pressure member 46 is inserted by finger pressure of the associated operating hand, wherein conical surfaces 36, 51 meet and the coupling slide 24 is displaced radially outward into its release position and the shaft 11 can be pulled out of the insertion hole 4a. The coupling of the shaft 11 takes place when inserted into the insertion hole 4a automatically by displacing the coupling slide 24 against the spring force and automatic engagement in the recess 26 in the shaft 11, the segment-shaped, z. B. as a secant groove, or may be annular.

The handpiece 100 shown in FIGS. 1 and 2 therefore has a number of different components, which are moved during operation or themselves

(to each other) to move the tool 12 by means of the motor 19 in the desired rotation. In addition, components or components are provided which are moved out of the head region 2 during the clamping or removal of the tool 12 in order to allow a secure grip of the tool or a release of this grip.

According to the present invention, it is now provided that moving parts of this handpiece 100 are provided with a chromium nitride (CrN) coating and / or a titanium nitride + gold coating. These are in particular those parts which are exposed to a higher load during operation since the surface properties of these components can be significantly improved with the aid of the chromium nitride or titanium nitride + gold coating.

Thus, the chromium nitride coating used according to the invention is characterized by the following properties:

a) a high hardness and adhesive strength, b) a very good chemical resistance, c) a high temperature resistance in air, d) a very low coefficient of friction compared to steel, e) a good sliding behavior with insufficient lubrication and heavy mechanical stress.

Another positive feature of the chromium nitride coating is that the application of relatively thick layers is easily possible. The application is preferably carried out by means of PVD (Physical Vapor Deposition) - technology, wherein readily layer thicknesses of up to 5 microns can be achieved. This in turn means that the chromium nitride coating also creates an additional reserve of wear for the coated components, since even over a longer period of use, coating of the components concerned remains ensured. In conjunction with the high hardness and low brittleness, this results in extremely high abrasion resistance for the coated parts. In addition, because the chromium nitride coating and the Increased corrosion resistance of the corresponding components, so their operating characteristics can be significantly improved.

The alternative or supplementary titanium nitride + gold coating initially consists of a titanium nitride layer (TiN), which is covered by a gold layer (Au). The titanium nitride layer has a thickness of up to 1 μm, while the gold layer is up to 0.5 μm thick. The application of the

Coating takes place with the PVD magnetron sputtering technique, which enables a reliable and uniform application of the coating to the affected components or components.

Special advantages of the titanium nitride + gold coating are:

a) a low total layer thickness of max. b) a significant increase in wear resistance, c) a high micro-surface hardness, d) an improved run-flat property due to the gold content in the case of insufficient lubrication, e) a significant reduction in friction and adhesion to the counterbody, and f) an increased service life extension due to the improved abrasion resistance.

Accordingly, in the handpiece 100 shown in FIGS. 1 and 2, it is intended to coat at least those components which are exposed to a higher load during operation due to surface contact with other components. These are in particular the shafts 3 of the drive mechanism or their coupling parts 3a and the components of the bevel gear 8. Furthermore, the bearing parts, ie the races of bearings used for supporting the shaft 3 3b and the bearing 5 could be coated for the drive sleeve 4 become. Another application of the coating according to the invention are the various components of the mechanism for clamping or coupling the tool 12, ie the various components of the clutches 9 and 11. All these components are exposed during operation of the handpiece 100 a relatively heavy load, as they are in surface contact with other elements and transmit forces. Due to the relatively easy to perform coating of these components with chromium nitride and / or titanium nitride + gold now their properties in terms of Increases wear, so that over a longer period of use, a reliable and error-free operation of the handpiece 100 is ensured.

As a second application example, a straight motor handpiece is presented, which is already known from DE 44 06 855 A1 of the Applicant. This handpiece is shown in FIGS. 3 and 4.

The rod-shaped, straight handpiece 101 consists of a rear motor part 102 with a built therein, in particular electric drive motor 103 and a front handpiece part 104, in the front of a machining tool with its shaft 105 can be clamped. For this purpose, a coaxially arranged in the handpiece part 104, sleeve-shaped, slotted collet 106, which is part of a drive shaft 107 which is rotatably mounted coaxially in the handpiece part 104 and is connected to the drive motor 103 to its rotation. The collet 106 can be opened and closed by a relative rotation between the motor part 102 and a grip sleeve 104a of the handpiece part 104. For this purpose, in the handpiece portion 104, an actuating mechanism 108 is integrated, which is effective between the grip sleeve 104a and the drive shaft 107 and has a gear 109, which converts the rotational movement of the grip sleeve 104a in an axial movement of a round tightening rod 110 extending from the rear coaxially through a Bearing sleeve 107a of the drive shaft 107 extends, is axially movably mounted in a bore and is screwed with its front end into an internal thread 106a of the collet 106. The grip sleeve 104a is mounted rotatably and longitudinally displaceably on a sleeve-shaped inner housing 111 about the longitudinal central axis 112 of the handpiece 101. In the inner housing 111, the drive shaft 107 is rotatably supported by means of two roller bearings 113, 114 having an axial spacing from each other. The motor part 102 can be connected by a cable 102a and possibly a connection part 102b to a power supply source and / or a control unit.

As in the embodiment according to FIGS. 1 and 2, it is provided that even with this straight motor handpiece 101, the moving or movable components, which are in surface contact and transmit force, with a Chromnitridbzw. Titanium nitride + gold coating are provided. In this case, therefore, the components of the various bearings 113, 114 and the collet 106 for clamping the tool shank 105 will be coated in the first place. Again, the parts already described above arise.

Finally, it should be pointed out again that the coating with chromium nitride and / or titanium nitride + gold on otherwise designed handpieces and Drive principles can be used. In particular, it would also be conceivable in the handpiece shown in FIGS. 1 and 2 to use an air turbine in the head region. Also in this case, the coating of the bearing parts for the turbine as well as the elements for clamping or holding the tool with chromium nitride or titanium nitride + gold would be conceivable, since in this case, the invention sought after advantages in terms of resistance to excessive wear of the various components.

Overall, therefore, it should be noted that the inventive proposal to coat components of a handpiece with chromium nitride and / or titanium nitride + gold, the properties of these components and thus the handpiece can be significantly improved overall. It is a particular advantage of the present invention is that the coating with chromium nitride or titanium nitride + gold can be carried out relatively easily and in high quality, so that the invention and the improvements sought thereby can be implemented in a simple but reliable manner ,

Claims

claims

1. Handpiece (100, 101), in particular for medical, dental or dental technical purposes, comprising a drive mechanism for a of the handpiece (100, 101) to be held tool (12, 105), wherein moving or movable parts of the handpiece (100 , 101) are at least partially provided with a coating, characterized in that the coating comprises chromium nitride and / or titanium nitride + gold.

2. Handpiece according to claim 1, characterized in that the handpiece (100, 101) comprises a device for selectively clamping or coupling of a drive mechanism to be moved by the tool (12, 105), wherein elements of this device with the chromium nitride or Titanium nitride + gold coating are provided.

3. Handpiece according to claim 2, characterized in that the device for clamping the tool (12, 105) has a collet (106).

4. Handpiece according to one of the preceding claims, characterized in that the tool (12, 105) is to put by means of the drive mechanism in a rotation.

5. Handpiece according to claim 4, characterized in that the drive mechanism for the tool (12, 105) at least one driven and rotatably mounted shaft (3, 107), wherein bearing elements (3a, 113, 114) for the shaft ( 3, 107) and / or coupling parts (3b, 8) are provided for rotation transmission with the chromium nitride or titanium nitride + gold coating.

6. Handpiece according to one of the preceding claims, characterized in that the chromium nitride coating has a thickness of up to 5μm.

7. Handpiece according to one of claims 1 to 5, characterized in that the titanium nitride + gold coating has a thickness of max. l, 5μm.

8. Handpiece according to one of the preceding claims, characterized in that it is a dental Bohrhandstück (100).

9. Handpiece according to one of claims 1 to 7, characterized in that it is a straight motor handpiece (101).