WO2003020152A1 - Configuration amelioree de tete de forage dentaire - Google Patents

Configuration amelioree de tete de forage dentaire Download PDF

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Publication number
WO2003020152A1
WO2003020152A1 PCT/IL2002/000735 IL0200735W WO03020152A1 WO 2003020152 A1 WO2003020152 A1 WO 2003020152A1 IL 0200735 W IL0200735 W IL 0200735W WO 03020152 A1 WO03020152 A1 WO 03020152A1
Authority
WO
WIPO (PCT)
Prior art keywords
spool
drill head
dental handpiece
proximal
bearing arrangement
Prior art date
Application number
PCT/IL2002/000735
Other languages
English (en)
Inventor
Gideon Sagi
Gadi Porat
Original Assignee
Micro Tools Ltd.
Medivice Systems Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Micro Tools Ltd., Medivice Systems Ltd. filed Critical Micro Tools Ltd.
Publication of WO2003020152A1 publication Critical patent/WO2003020152A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C1/00—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design
    • A61C1/08—Machine parts specially adapted for dentistry
    • A61C1/18—Flexible shafts; Clutches or the like; Bearings or lubricating arrangements; Drives or transmissions
    • A61C1/181—Bearings or lubricating arrangements, e.g. air-cushion bearings
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C1/00—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design
    • A61C1/02—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design characterised by the drive of the dental tools
    • A61C1/05—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design characterised by the drive of the dental tools with turbine drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
    • F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
    • F16C17/105—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure with at least one bearing surface providing angular contact, e.g. conical or spherical bearing surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
    • F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
    • F16C17/107—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure with at least one surface for radial load and at least one surface for axial load
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C1/00—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design
    • A61C1/08—Machine parts specially adapted for dentistry
    • A61C1/18—Flexible shafts; Clutches or the like; Bearings or lubricating arrangements; Drives or transmissions
    • A61C1/181—Bearings or lubricating arrangements, e.g. air-cushion bearings
    • A61C1/183—Jewel bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2316/00—Apparatus in health or amusement
    • F16C2316/10—Apparatus in health or amusement in medical appliances, e.g. in diagnosis, dentistry, instruments, prostheses, medical imaging appliances
    • F16C2316/13—Dental machines

Definitions

  • the present invention relates to a drill head for a dental apparatus, in particular such a drill head comprising at least one aerodynamic bearing.
  • dental drill heads generally comprise a rotor assembly having a shaft carrying a rotor, and a tool releasably secured on the shaft.
  • Such tools are generally multi-usable and sterilisable typically by autoclave.
  • the term rotor includes impellers and any type of turbine configuration for providing high-speed rotation of the rotor shaft by the action of a stream of pressurised gas, typically air, thereon.
  • the shaft also generally comprises ball bearings, bushings or other annular bearings on either axial side of the rotor for rotatably mounting the same in a casing.
  • Jewel bearings include any type of hardened bearing in the form of a cup or indentation on a first member which receives a hardened point comprised on a second member, enabling relative angular or rotational motion between the first and second members.
  • WO 01/1879 the contents of which are incorporated herein in their entirety for all purposes as if fully set forth herein, provides a dental drill head having a special proximal jewel bearing arrangement wherein chucks may be actuated via the distal end of the head. While such an arrangement has the advantage of reducing noise relative to ball bearing arrangements, considerable heating between the hardened point and indentation occurs, which is in itself undesirable and moreover limits the upper operating rotational speed of the rotor.
  • static air bearing configuration typically in the form of an annular bearing having bearing surfaces substantially parallel to the axis of rotation or in frustro-conical arrangement, such as described in US 3,210,848, for example.
  • static air bearings are easily deflected off-axis when a lateral force is applied (such as when pressing the tool against a tooth in a lateral direction). This results in non-uniform distribution of the airflow around the bearing and in inefficient running of the bearing, and incurs dynamic imbalance of the rotor shaft, which may have negative consequences.
  • static air bearings require externally pressurised air source and thus require an air feed arrangement from the compressor that services the rotor. This requires special ducting within the drill head, and moreover usually results in the ejection of air from the bearing into the environment close to the dental practitioner, further increasing the level of noise generated.
  • a drill head comprising one annular aerodynamic bearing arrangement mounted onto the rotor, preferably at the distal end thereof.
  • the rotor also enables the selective mounting and dismounting of a distal dental tool via a chuck that is actuable from a proximal end of the head, as in conventional heads.
  • the rotor shaft also comprises a second aerodynamic bearing arrangement at the proximal end thereof, but may include other types of bearing arrangements instead.
  • the magnitudes and frequencies of the noise generated thereby are substantially reduced with respect to other types of rotor bearings, and does not suffer from the problems of jewel bearings or static air bearings.
  • the aerodynamic bearing arrangement comprises a stationary part and a moving part having mutually facing bearing surfaces, wherein one of the mutually facing bearing surfaces is relatively smooth and the other bearing surface comprises suitable surface features such that when the moving part rotates with respect to the stationary part at rotational speeds above a minimum threshold, dynamic pressure is created between the mutually rotating bearing surfaces, providing a cushioning layer of air (or alternatively " of another gas, when another gas is used in place " of air) therebetween.
  • These surface features may take any one of a number of different forms, and may comprise, for example, a plurality of grooves or protrusions, for example as described in US 4,998,033, the contents of which are incorporated herein in their entirety for all purposes as if fully set forth herein.
  • the aforesaid surface features may comprise a plurality of suitable surface micropores, for example as described in US 6,046,430, the contents of which are incorporated herein in their entirety for all purposes as if fully set forth herein.
  • the present invention relates to a drill head for a dental handpiece comprising a casing and a spool, said spool comprising a distal bearing arrangement, a rotor assembly and a proximal bearing arrangement in series along a common longitudinal axis such as to enable rotation of the spool within said casing, characterised in that at least one of said distal bearing arrangement or said proximal bearing arrangement comprises an aerodynamic bearing arrangement having a stationary part and a moving part, wherein said stationary part is comprised within said casing and said moving part is comprised on said spool .
  • the present invention is thus also directed to a corresponding spool for a dental handpiece drill head comprising a spool, said spool comprising a distal bearing arrangement, a rotor assembly and a proximal bearing arrangement in series along a common longitudinal axis such as to enable rotation of the spool within casing of the drill head, characterised in that at least one of said distal bearing arrangement or said proximal bearing arrangement comprises an aerodynamic bearing arrangement having a stationary part and a moving part, wherein said stationary part is adapted for mounting within a suitable drill " head casing and said moving part is comprised on said spool .
  • the distal bearing arrangement, said rotor assembly and said proximal bearing arrangement are serially mounted longitudinally on a common shaft.
  • the distal bearing arrangement constitutes a said aerodynamic bearing arrangement having a stationary part and a moving part, wherein said stationary part is mounted internally to a distal part of said casing and said moving part is mounted to a distal part of said shaft.
  • the moving part comprises a convex bearing surface having a shape corresponding to a surface of revolution generated by an arcuate profile displaced from said axis.
  • the convex bearing surface may comprise a portion of a sphere having its center of curvature along said axis.
  • the moving part comprises a convex frustro-conical bearing surface having an axis of revolution coaxial with said axis.
  • the convex bearing surface may diverge laterally in a proximal direction along said axis.
  • the moving part may comprise a convex cylindrical bearing surface having an axis of revolution coaxial with said axis.
  • the moving part may further comprise a planar annular distal bearing surface substantially perpendicular to said axis.
  • the stationary part typically comprises a substantially concave bearing surface substantially complementary to the said convex bearing surface of the moving part, such as to provide a thin uniform gap therebetween when said aerodynamic bearing is in operation.
  • the stationary part may further comprise a substantially planar proximal annular bearing surface complementary to the said distal bearing surface of the moving part, such as to provide a thin uniform gap therebetween when said aerodynamic bearing is in operation.
  • the convex bearing surface comprises suitable surface features for generating aerodynamic dynamic pressure, and wherein the said concave bearing “ surface “ is “ “ substantially smooth.
  • the convex bearing surface is substantially smooth and the said concave bearing surface comprises suitable surface features for generating aerodynamic dynamic pressure.
  • the distal bearing surface comprises suitable surface features for generating aerodynamic dynamic pressure, and wherein the said proximal bearing surface is substantially smooth.
  • the proximal bearing surface is substantially smooth and the said distal bearing surface comprises a plurality of grooves for generating aerodynamic dynamic pressure.
  • the said suitable surface features comprise a plurality of grooves for generating aerodynamic dynamic pressure.
  • the grooves are typically in the form of spiral channels.
  • the grooves may be of a shape and profile such that when the said aerodynamic bearing is in operation the aerodynamic pressure generated thereby acts inwards, so that air is channeled from inside the head in a generally distal direction towards the outside of the head.
  • the suitable surface features comprise a plurality of suitable micropores for generating aerodynamic dynamic pressure.
  • the stationary part and said moving part are made from a hard material, and at least one of said stationary part and said moving part is made from a suitable ceramics material or from a suitable metal including stainless steel.
  • at least one of said stationary part and said moving part comprises a coating made from a friction-reducing material including Teflon.
  • the drill head casing typically comprises suitable proximal and distal openings.
  • the proximal bearing arrangement typically comprises a suitable annular bearing arrangement mounted proximally onto said shaft for rotation thereof relative to said casing.
  • the annular bearing arrangement comprises at least one suitable ball bearing suitably mounted to said casing and to said shaft for rotation therebetween.
  • the annular bearing arrangement comprises at least one suitable annular bushing suitably mounted to said casing and to said shaft f ⁇ r rotation therebetween, where ⁇ rT said bushing is optionally made from a self-lubricating material or from a suitable metal and coated with a layer of self-lubricating material on the surface in contact with a rotating member.
  • the proximal bearing arrangement comprises a jewel bearing mounted at a proximal end of said casing for axial reciprocation with respect thereto, said jewel bearing adapted for receiving a pointed bearing end comprised at the proximal end of said shaft, said jewel bearing capable of moving by at least a first displacement from a proximal position to a distal position in response to a suitable external axial force applied to said jewel bearing.
  • the proximal bearing arrangement constitutes a said aerodynamic bearing arrangement having a stationary part and a moving part, wherein said stationary part is mounted internally to a distal part of said casing and said moving part is mounted to a proximal part of said shaft, similar to the distal aerodynamic bearing arrangement, mutatis mutandis.
  • the shaft preferably has an open distal end and is further adapted to accommodate therein a tool shaft of a dental tool.
  • the drill head may further comprise a chuck assembly for selectively clamping and releasing a tool shaft within said shaft.
  • the chuck assembly may be actuable via an actuator push-button mounted onto a proximal end of said head, said button comprising a digitally actuable portion thereof axially extending in a proximal direction substantially beyond said proximal opening, and further comprising means for hmiting proximal movement of said push-button with respect to said casing.
  • Each element of the drill head is preferably made from a material that is sterilisable at least by autoclave means to a temperature of at least about 135°C, and preferably up to at least about 200°C.
  • Figure 1 shows in side elevational cross-sectional view, a preferred embodiment of the present invention comprising a distal aerodynamic bearing arrangement accommodated in the drill head.
  • Figure 2 shows in end view the spool of the embodiment of Figure 1.
  • Figure 3 shows in side elevational view the spool of the embodiment of Figure 1.
  • Figure 4 shows in fractured side elevational cross-sectional view an alternative configuration of the spool of the embodiment of Figure 1.
  • Figure 5 shows in fractured side elevational cross-sectional view another alternative configuration of the spool of the embodiment of Figure 1.
  • Figure 6 shows in fractured side elevational cross-sectional view another alternative configuration of the spool of the embodiment of Figure 1.
  • Figure 7 shows in side elevational cross-sectional view another alternative configuration of the spool of the embodiment of Figure 1.
  • Figure 8 shows in side elevational cross-sectional view another alternative configuration of the spool of the embodiment of Figure 1.
  • Figure 9 shows the embodiment of Figure 1 comprising an air feed arrangement for providing air to the aerodynamic bearing arrangement.
  • Figure 10 shows the embodiment of Figure 1 comprising another air feed arrangement for providing air to the aerodynamic bearing arrangement. Disclosure of Invention
  • the present invention relates to a drill head for a dental handpiece, the drill head comprising a rotor mounted for rotation therein via a distal and a proximal bearing arrangement, and characterised in that at least one the bearing arrangements, and in particular the distal bearing arrangement, is a suitable aerodynamic bearing arrangement, which when made from suitable materials provides substantial advantages for reducing vibration and noise relative to annular ball or roller bearing, static air bearings and other types of bearings used in the art.
  • the present invention is also directed to a spool used with such a drill head, in which the spool comprises the rotor and the proximal and distal bearing arrangements.
  • aerodynamic bearing is used herein interchangeably with gas dynamic bearing and hydrodynamic bearing.
  • aerodynamic bearing is herein taken to refer to the type of bearing having a stationary part and a moving part having mutually facing dynamic pressure generating bearing surfaces, wherein one of the mutually facing bearing surfaces is relatively smooth and the other bearing surface comprises any suitable surface features such that, when the moving part rotates with respect to the stationary part at rotational speeds above a minimum threshold, dynamic pressure is created in the air (or another suitable gas) between the mutually rotating bearing surfaces, providing a cushioning layer of air (or the other gas) therebetween.
  • These surface features may thus comprise, for example, a plurality of grooves or protrusions, for example as described in US 4,998,033, or alternatively, a plurality of suitable surface micropores, for example as described in US 6,046,430.
  • proximal and distal respectively designated (P) and (D) in the Figures, herein refer to directions away from and towards the tooth of a dental patient.
  • a dental tool such as a drill would be inserted proximally into the distal end of the drill head.
  • FIG. 1 illustrates a preferred embodiment of the present invention.
  • the drill head designated by the numeral (10) is typically comprised at the distal end of dental instrument, generally a handpiece (100).
  • the handpiece (100) comprises at least one air line (120) for providing a compressed gas, usually air, from a compressor to the turbine rotor (20) comprised in head (10).
  • the term rotor herein includes, and is thus used herein interchangeably with, any suitable impeller or any type of turbine configuration capable of being rotated about its axis (15) by means of the action of a stream of pressurised gas, typically air, onto or through the rotor.
  • One or more return lines enable the gas (or air) to be removed from the head (10) after providing rotational energy to the rotor (20).
  • the handpiece (100) further optionally comprises at least one lubricating fluid line (130) for directing at least one jet of lubricating/coolant liquid towards the point of contact between a dental tool (50) that may be comprised in said head (10) and a tooth.
  • the handpiece (100) further optionally comprises a fibre optic line or light (not shown) for illuminating the dental area of interest.
  • the said head (10) comprises a spool comprising a distal bearing arrangement, a rotor assembly a proximal bearing arrangement and a distal bearing arrangement serially mounted longitudinally on a shaft.
  • the rotor assembly comprises said turbine rotor (20) rotatably mounted within a casing (60), typically via a shaft (29) about a turning axis (15), said casing (60) comprising suitable proximal and distal openings, (64) and (69) respectively.
  • the rotor (20) comprises a plurality of vanes (21), typically an odd number thereof, adapted for enabling said rotor (20) to revolve about axis (15) on the application of a suitable gas current thereto, typically compressed air, via air line (120).
  • Said rotor (20) is mounted onto a shaft (29) for rotation therewith, said shaft (29) having at least a hollow portion (22) extending axially from a distal end of said rotor (20) in a proximal direction.
  • Said shaft (29) also comprises a proximal end (24) extending axially from a proximal end of said rotor (20).
  • At least a portion of said shaft (29), and particularly said hollow shaft portion (22) are adapted for receiving a tool shaft (52) of a dental tool (50), such as a drill or bur, and thus may comprise a clamping sleeve (27) having an internal diameter which closely matches, but is typically not less than, the external diameter of the tool shaft (52).
  • the drill head (10) comprises a distal aerodynamic bearing arrangement (200) and a conventional proximal bearing arrangement.
  • the distal annular aerodynamic bearing arrangement (200) is mounted onto said hollow shaft portion (22) to provide for rotation therewith relative to said casing (60), as is described below in greater detail, said hollow shaft portion (22) being in axial registry with said distal opening (69).
  • said hollow shaft portion (22) axially extends at least in a distal direction substantially beyond said distal opening (69) of said casing.
  • the distal aerodynamic bearing arrangement (200) comprises a stationary part (210), mounted with respect to an internal distal part of the casing (60), and a moving part (220) mounted onto the distal hollow shaft portion (22) of the " shaft (20).
  • the moving part (220) has a convex bearing surface (225) is in the shape of a body of revolution about axis (15), such as generated by an arcuate profile displaced from said axis (15), such a profile being defined in planes parallel to and passing through the said axis (15).
  • the convex bearing surface (225) may be substantially hemispherical, or at least comprise part of the surface of a sphere having its center of curvature (C) on axis (15), diverging laterally outwards in a proximal direction from its distal pole, which is of course hollow to permit the protrusion therethrough of the distal end of shaft (20).
  • the stationary part (210) comprises a substantially concave bearing surface (215) complementary to the convex bearing surface (225) of the moving part (220), such as to provide a thin uniform gap (235), typically about 5 microns, between these two facing bearing surfaces when the aerodynamic bearing arrangement (200) is assembled.
  • the gap (235) is shown in the figures exaggerated and out of scale with respect to the bearing arrangement (200).
  • one of the two bearing surfaces preferably the convex bearing surface (225), comprises a plurality of grooves (230) for generating aerodynamic dynamic pressure
  • the other bearing surface in the preferred embodiment, the concave bearing surface (215)
  • the convex bearing surface (225) may be relatively smooth and the concave bearing surface (215) comprises a plurality of said grooves (230) for generating aerodynamic dynamic pressure.
  • the grooves (230) are typically in the form of spirals.
  • one of the said bearing surfaces (225) or (215) comprises other suitable surface features instead of the said grooves (230), mutatis mutandis, such that, when the moving part rotates with respect to the stationary part at rotational speeds above a minimum threshold, dynamic pressure is created in the air (or another suitable gas) between the mutually rotating bearing surfaces (225), (215), providing a cushioning layer of air (or the other gas) therebetween.
  • suitable " surface features include a plurality of suitable protrusions, or alternatively a plurality of micropores, for example as described in US 6,046,430.
  • the grooves (230) are of a shape and profile such that the aerodynamic pressure generated acts inwards, so that air is sucked from outside the head (10) in a proximal direction towards the inside of the head (10). This reduces the noise level further and prevents ejection of foreign matter from inside the drill to the patient. On the other hand, such an arrangement may result in dirt and other debris being ingested into the drill head, which may damage or contaminate the same.
  • the grooves (230) are of a shape and profile such that the aerodynamic pressure generated acts outwards, so that air flows from inside the head (10) in a distal direction towards the outside of the head (10).
  • the said drill head (10) may comprise an air feed pipe (140) for providing gaseous communication between the concave bearing surface (225) and the air line (120) via the inside of the head (10), thus enabling air within the head (10) to flow inbetween the bearing surfaces (215), (225).
  • the said drill head (10) may comprise an air feed pipe (145) which provides direct gaseous communication between the concave bearing surface (225) and the air line (120).
  • entry of air into the aerodynamic air bearing arrangement (200) may be via the air feed pipes (140) or (145), rather than the hub or outer perimeter of the bearing.
  • the substantially spherical profile of the bearing surfaces (215), (225) facilitates the relative alignment therebetween, and enables some lateral movement due to a lateral force acting on a tool (50), to be accommodated by a degree of swinging between the bearing surfaces (215), (225) about center of curvature (C).
  • the distal bearing arrangement may comprise a stationary part and a complementary moving part different in configuration to that described for the preferred embodiment.
  • the moving part (220A) comprises a convex frustro-conical bearing surface (225A) having an axis of revolution substantially coaxial with axis (15)
  • the stationary part (210A) comprises a complementary concave frustro-conical bearing surface (215A).
  • the said convex bearing surface (225A) comprises a plurality of grooves (230A) for generating aerodynamic dynamic pressure and said concave bearing surface (215A) is relatively smooth.
  • the convex bearing surface (225A) is relatively smooth and the concave bearing surface (215A) comprises said grooves (230A).
  • the moving part (220B) comprises a convex cylindrical bearing surface (225B) having its axis of revolution substantially coaxial with said axis (15), and the stationary part (210B) comprises a complementary concave cylindrical bearing surface (215B).
  • the said convex bearing surface (225B) comprises a plurahty of grooves (230B) for generating aerodynamic dynamic pressure and said concave bearing surface (215B) is relatively smooth.
  • the convex bearing surface (225B) is relatively smooth and the concave bearing surface (215B) comprises said grooves (23 OB).
  • the moving part (220C) comprises a convex cylindrical bearing surface (225C1) as well as a distal planar annular bearing surface (225C2), both having their axis of symmetry coaxial with axis (15).
  • the stationary parts (210C1) and (210C2) may be integrally or otherwise joined together.
  • the said convex bearing surface (225C1) comprises a plurality of grooves (230C1) for generating aerodynamic dynamic pressure and said concave bearing surface (215C1) is relatively smooth.
  • the convex bearing surface (225C1) is relatively smooth and the concave bearing surface (215C1) comprises said grooves (230C1).
  • the said bearing surface (225C2) comprises a plurality of grooves (230C2) for generating aerodynamic dynamic pressure and said bearing surface (215C2) is relatively smooth.
  • the bearing surface (225C2) is relatively smooth and the bearing surface (215C2) comprises said grooves (230C2).
  • the magnitude of the gap (235C1) between surfaces (215C1) and (225C1), and the gap (235C2) between surface (215C2) and (225C2) when the spool (20) is rotating within head (10) may be substantially the same or different one from the other.
  • one of the corresponding said bearing surfaces thereof may comprises other suitable surface features instead of the corresponding grooves, mutatis mutandis, such that, when the moving part rotates with respect to the stationary part at rotational speeds above a minimum threshold, dynamic pressure is created in the air (or another suitable gas) between the corresponding mutually rotating bearing surfaces to provide a cushioning layer of air (or the other gas) therebetween.
  • suitable surface features for these embodiments include a plurality of suitable protrusions, or alternatively a plurahty of micropores, for example as described in US 6,046,430.
  • the aerodynamic bearing (200) is preferably made form any suitable hard material, including a ceramic or metal such as stainless steel for example, and at least one of the bearing surfaces thereof may be coated with a suitable coating such as Teflon to reduce friction and wear at the startup and wind-down phases of the rotor.
  • the aerodynamic bearing is capable of being heated to at least 200 °C without experiencing any significant distortions, particularly in the bearing surfaces thereof.
  • Said bearing arrangement (300) is preferably made from a suitable material, also capable of being sterilised, particularly by any suitable autoclave means up to at least 135°C, and preferably up to at least 200° C.
  • the said proximal bearing arrangement (300) comprise a conventional bearing arrangement, typically a ball-bearing arrangement.
  • the proximal bearing arrangement (300) may comprise a roller bearing arrangement, annular bushing arrangement, for example, or any other suitable annular arrangement known in the art of dental drills for supporting the rotor (20) proximally for rotation with respect to the casing (60).
  • the said proximal bearing arrangement (300) comprises at least one suitable annular ball bearing arrangement (310) having an inner race mounted on shaft (29), an outer race mounted in said casing (60), and a number of balls disposed therebetween (not shown).
  • a typically annular silicone washer or 'O'-ring (219) adapted for sealing between said proximal bearing arrangement (300) and said casing (60) is provided.
  • said proximal bearing arrangement (300) may comprise at least one suitable bush bearing suitably mounted to said casing (60) and to said hollow shaft (29) for rotation therebetween.
  • a bush bearing is preferably made from a self-lubricating hard material, capable of being sterilised, particularly by any suitable autoclave means up to at least 135°C, and preferably up to at least 200°C.
  • Said annular bushing may be made from any suitable hard and preferably self lubricating material, including ceramic, composite and plastics materials, and also including suitable metals particularly sintered metals.
  • said annular bushing may be made from any one of the following plastic materials:- Nyliner ® (manufactured by Thomson); Aurum ® (manufactured by Mitsui Toatsu Chemicals Inc.); Iglide ® or Drylin ® (manufactured by Igus); Acetron ® (manufactured by Orkot); Rulon ® or Meldin ® (manufactured by Furon); or alternatively from any of the following ceramic materials:-Cerbec ® (manufactured by Norton Advanced Ceramics); or alternatively from any of the following composite materials:- Wearcomp ® (manufactured by Hycomp); Garlock ® (manufactured by Coltec Industries); Luytex ® (manufactured by Orkot); Duralon (manufactured by Rexnord corporation); or alternatively from any one of the following metallic materials :- Graphalloy ® (manufactured by
  • said annular bushing may be made from a suitable metal and coated with a laye of self-lubricating material on the surface in contact with a rotating member.
  • Said self-lubricating layer may be made, for example, from Simplicity ® (manufactured by Pacific Bearings), Teflon ® or Frelon ® .
  • the said proximal bearing arrangement (300) comprises a jewel bearing arrangement at the said proximal end (24), preferably similar to that described in WO 01/1879, mutatis mutandis.
  • the proximal end (24) may be in the form of a stub shaft, preferably configured for axial reciprocation with respect to said rotor (20) and comprises a hardened pointed bearing end (28) at the proximal end of the shaft (29).
  • a cup-shaped or conical jewel bearing (70) is mounted at the proximal end of said casing (60) adapted for receiving and seating thereat said pointed bearing end (28) of said shaft (29).
  • the jewel bearing (70) is thus preferably capable of moving by a suitable displacement from a proximal position to a distal position by means of an external axial force applied to said jewel bearing (70) via proximal opening (64) comprised in said casing (60).
  • Optional spring means may also be provided for returning said jewel bearing (70) to said proximal position in the absence of the externally applied axial force thereto.
  • the said proximal bearing arrangement (300) comprises a second aerodynamic bearing arrangement (200'). In the illustrated embodiment, details of the casing (60) and so on are not shown for clarity.
  • the second aerodynamic bearing arrangement (200') comprises a stationary part mounted to the casing (60) and a moving part mounted to the proximal end (24) of the shaft (29), similar to those described with respect to the distal aerodynamic bearing arrangement, with reference to Figures 1 to 6, mutatis mutandis.
  • the second aerodynamic bearing arrangement (200') comprises a moving part (220') having a convex bearing surface (225') is in the shape of a body of revolution about axis (15), having an arcuate profile in planes parallel to and passing through the said axis (15).
  • the convex sliding surface (225') has an arcuate profile, diverging laterally outwards in a distal direction from its proximal pole, which is of course hollow to permit the protrusion therethrough of the proximal end of shaft (29).
  • the stationary part (210') comprises a substantially concave bearing surface (215') complementary to the convex bearing surface (225') of the moving part (220'), such as to provide a suitable thin uniform gap between these two bearing surfaces when the second aerodynamic bearing arrangement (200') is assembled.
  • One of the two bearing surfaces preferably the convex bearing surface (225'), comprises a plurality of grooves (230'), or alternatively other suitable surface ' feature such as protrusions or micropores, for example, mutatis mutandis, for generating aerodynamic dynamic pressure.
  • the other bearing surface in the preferred embodiment, the concave bearing surface (215'), is relatively smooth.
  • the convex bearing surface (225') may be relatively smooth and the concave bearing surface (215') comprises a plurality of grooves (230'), or alternatively other suitable surface feature such as protrusions or micropores, for example, mutatis mutandis, for generating aerodynamic dynamic pressure.
  • the grooves (230') are typically in the form of spirals.
  • the grooves (230) are of a shape and profile such that the aerodynamic pressure generated acts inwards, so that air is sucked from outside the head (10) in a proximal direction towards the inside of the head (10).
  • the grooves (230) are of a shape and profile such that the aerodynamic pressure generated acts outwards, so that air flows from inside the head (10) in a general distal direction towards the outside of the head (10).
  • the sliding surfaces (215), (225) of the distal bearing arrangement (300), and the bearing surfaces (215'), (225') of the proximal second aerodynamic bearing arrangement comprise arcuate profiles in planes through parallel to and intersecting the axis (15) such as to facilitate the relative alignment therebetween these components. More preferably, such arcuate profiles are circular, having displaced centers of curvature (PI), (P2), on the axis (15).
  • the circular profiles may have a common center of curvature on the axis (15) - in other words, the bearing surfaces (215), (225) of the distal bearing arrangement (300), and the bearing surfaces (215'), (225') of the proximal second aerodynamic bearing arrangement (200') each comprise a portion of the outer surface of an imaginary common sphere having its center of curvature (P) on axis (15).
  • This allows some lateral movement of the shaft (29), due to a lateral force acting on a tool (50) for example, to be accommodated by a degree of swingin between the bearing surfaces (215), (225) and between bearing surfaces (215'), (225') about (P) on axis (15).
  • the second aerodynamic bearing (300) is preferably made form any suitable hard material, including a ceramic or metal such as stainless steel for example, and at least one of the bearing surfaces thereof may be coated with a suitable coating such as Teflon to reduce friction and wear at the start-up and wind-down phases of the rotor.
  • the aerodynamic bearing (300) is capable of being heated to at least 200 °C without experiencing any significant distortions, particularly in the bearing surfaces thereof.
  • any permutation of configurations of aerodynamic bearing arrangements may be used for the distal and proximal aerodynamic arrangements.
  • the aerodynamic bearing arrangement illustrated in Figure 6 may be used as a proximal aerodynamic bearing arrangement, mutatis mutandis, together with the distal aerodynamic bearing arrangement illustrated in Figure 4, and so on, mutatis mutandis.
  • a single aerodynamic bearing arrangement may be used at the proximal end of the shaft (29), similar to any one of the configurations illustrated in Figures 1 to 6, for example, mutatis mutandis, with a conventional bearing arrangement at the distal end of the shaft, as described herein with respect to the proximal end of the shaft, for example, mutatis mutandis.
  • the proximal opening (64) of said casing (60) is comprised in a proximal annular cap (80), which is releasably mountable to the proximal end of said casing (60) by any suitable means such as, for example, mutually engageable threaded facing surfaces on said cap (80) and casing (60).
  • a typically annular silicone washer or 'O'-ring (82) adapted for sealing between said cap (80) and said casing (60) is provided.
  • the cap (80) comprises an actuator push-button portion (92) proximal to said proximal end (24).
  • Said button (92) axially extends in a proximal direction substantially beyond said proximal opening (64).
  • Said button (92) is actuable digitally, i.e., by means of a finger or thumb of a user.
  • the said drill head (10) preferably further optionally comprises a washer (not shown) adapted for sealing between said push-button portion (92) and said proximal opening (64) of said cap (80), and for absorbing noise and vibration.
  • a washer is typically made from silicone, and is capable of being sterilised by autoclave means up to at least 135°C, and preferably up to at least 200°C.
  • Such sealing is advantageous in substantially preventing air (or gas) leakage from the casing (60) when the head (10) is being used, and therefore this washer need only seal between said push-button portion (92) and said proximal opening (64) of said cap (80), at least when said push-button portion (92) is positioned at said proximal position as illustrated for example in Figure 1.
  • said washer need not be in sealing contact with the distal end of said push-button (92).
  • spring means (85) may be provided for returning said push button (92) to said proximal position in the absence of the externally applied axial force thereto.
  • the said push button (92) may optionally comprise a substantially annular well (94) at the distal end thereof accommodating the proximal end of a helical spring (85).
  • the distal end of the spring (85) is seated on a suitable annular plate or shoulder (74) comprised in said casing (60).
  • the said drill head (10) further comprises a suitable chuck assembly having suitable actuation means (not shown), characterised in being axially movable by a displacement between a first proximal axial position and a second distal axial position and adapted for enabling a suitable tool shaft (52) of a tool (50) to be respectively secured within and released from said hollow shaft (22).
  • Said chuck assembly may comprise said clamping sleeve, which is specially adapted for securing or releasing the tool shaft (52). Examples of such chuck assembly axially actuable via such axially reciprocating actuation means are common and need not be described further herein.
  • Said actuation means are axially coupled with said push button (92) for movement therewith such as to provide a suitable displacement to the chuck.
  • Said chuck assembly is typically made from stainless steel.
  • each element of said head (10) is made from a material that is sterilisable at least by autoclave means to a temperature of at least 135°C, and preferably at least to 200°C. While in the foregoing description describes in detail only a few specific embodiments of the invention, it will be understood by those skilled in the art that the invention is not limited thereto and that other variations in form and details may be possible without departing from the scope and spirit of the invention herein disclosed.

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  • Health & Medical Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Engineering & Computer Science (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Mechanical Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Physics & Mathematics (AREA)
  • Dentistry (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Dental Tools And Instruments Or Auxiliary Dental Instruments (AREA)

Abstract

L'invention concerne une tête de forage améliorée et une bobine prévue à cet effet dotée d'un dispositif de palier aérodynamique annulaire monté sur le rotor, de préférence au niveau de son extrémité distale. Généralement, le rotor permet également le montage et le démontage sélectifs d'un outil dentaire distal par l'intermédiaire d'un mandrin actionné depuis l'extrémité proximale de la tête, comme dans les têtes classiques. L'arbre rotor comporte également, de préférence, un second dispositif de palier aérodynamique au niveau de son extrémité proximale, mais peut également comprendre d'autres types de dispositifs de palier. Dans la tête de forage améliorée de l'invention, l'amplitude et les fréquences du bruit généré par celle-ci sont sensiblement réduites par rapport à d'autres types de paliers de rotor, et ladite tête ne présente pas les inconvénients des têtes à montages sur rubis ou à paliers à air statiques.
PCT/IL2002/000735 2001-09-06 2002-09-04 Configuration amelioree de tete de forage dentaire WO2003020152A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IL14532101A IL145321A0 (en) 2001-09-06 2001-09-06 Improved dental drill head configuration
IL145321 2001-09-06

Publications (1)

Publication Number Publication Date
WO2003020152A1 true WO2003020152A1 (fr) 2003-03-13

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IL (1) IL145321A0 (fr)
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006053153A1 (fr) * 2004-11-12 2006-05-18 Dentsply International Inc. Piece a main dentaire avec des roulements ailes
US8562343B2 (en) 2010-06-11 2013-10-22 Allan Magneson Fluid driven dental handpiece with hydrostatic bearings

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3210848A (en) 1962-10-11 1965-10-12 Sperry Rand Corp Handpiece of the air impulse turbine type
US3306375A (en) * 1964-01-09 1967-02-28 Macks Elmer Fred High-speed handpiece
US3310285A (en) * 1962-11-15 1967-03-21 Hawtin Percy Dental handpiece
US3391902A (en) * 1965-06-29 1968-07-09 William C. Dee Air bearings for the turbines of dental drills and the like
US4998033A (en) 1989-04-12 1991-03-05 Ebara Corporation Gas dynamic bearing for spindle motor
US6046430A (en) 1996-09-30 2000-04-04 Surface Technologies Ltd. Bearing having micropores, and design method therefor
WO2001001879A1 (fr) 1999-07-01 2001-01-11 Medivice Systems Ltd. Tete de fraise dentaire

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3210848A (en) 1962-10-11 1965-10-12 Sperry Rand Corp Handpiece of the air impulse turbine type
US3310285A (en) * 1962-11-15 1967-03-21 Hawtin Percy Dental handpiece
US3306375A (en) * 1964-01-09 1967-02-28 Macks Elmer Fred High-speed handpiece
US3391902A (en) * 1965-06-29 1968-07-09 William C. Dee Air bearings for the turbines of dental drills and the like
US4998033A (en) 1989-04-12 1991-03-05 Ebara Corporation Gas dynamic bearing for spindle motor
US6046430A (en) 1996-09-30 2000-04-04 Surface Technologies Ltd. Bearing having micropores, and design method therefor
WO2001001879A1 (fr) 1999-07-01 2001-01-11 Medivice Systems Ltd. Tete de fraise dentaire

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006053153A1 (fr) * 2004-11-12 2006-05-18 Dentsply International Inc. Piece a main dentaire avec des roulements ailes
US8562343B2 (en) 2010-06-11 2013-10-22 Allan Magneson Fluid driven dental handpiece with hydrostatic bearings

Also Published As

Publication number Publication date
IL145321A0 (en) 2002-06-30

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