US2895738A

US2895738A - Dental drill chuck

Info

Publication number: US2895738A
Application number: US762536A
Authority: US
Inventors: Robert N Baker
Original assignee: Bowen & Co Inc
Current assignee: Bowen & Co Inc; Bowen & Company Inc
Priority date: 1958-09-22
Filing date: 1958-09-22
Publication date: 1959-07-21
Anticipated expiration: 1976-07-21

Description

July 21, 1959 BAKER 2,895,738

DENTAL DRILL CHUCK Filed Sept. 22, 1958 fl/A 42 1 /2 & 4 I I Z 5 z a i j- I a l I z INVENTOR. R0361? M Baker BY A TTURNE Y5 United States Patent DENTAL DRILL CHUCK Robert N. Baker, Kings Mountain, N.C., assignor to Bowen & Company, Inc., Rockville, Md., a corporation of Delaware Application September 22, 1958, Serial No. 762,536

8 Claims. (Cl. 279-1) This invention relates to dental drills, and particularly to dental drills wherein a tool is mounted on and driven by a high speed fluid turbine. It is to be understood, however, that the invention may be employed in rotary K1018 other than those designed especially for dental Work.

In previous dental tools of this type, difliculty and inconvenience were encountered in mounting and removing dilferent tools from the turbine because the turbine was enclosed in a housing and most tools were threadedly engaged with holding means on the turbine Shaft. To mount or remove such tools it was necessary to employ a wrench or similar instrumentality to hold the turbine stationary while the tool was mounted or removed.

According to the present invention means are provided whereby a tool may be readily removed from threaded engagement with such turbine by merely applying manual pressure to a portion of the turbine housing. The turbine shaft is hollow and provided at one end with a conical surface for frictionally engaging a portion of the tool, the shaft of which is threadedly engaged with a member slidable in the hollow shaft. The slidable memher is resiliently urged in a direction to frictionally engage the tool shank with the conical surface but can be moved in the other direction to disengage the tool shank from the conical surface by applying manual pressure to a projecting end of the slidable member. The projecting end is covered by a. resilient diaphragm fixed to the turbine housing so that the application of manual pressure thereto not only moves the tool axially out of frictional engagement with the .conical surface but also holds the slidable member against rotation so that the tool may then be readily unscrewed therefrom.

It is therefore an object of this invention to provide holding means for a dental tool driven by a high speed fluid turbine wherein no special tools are required for mounting or demounting the tool.

Another .object of the invention is to provide a dental tool mounting including a friction drive and means for readily releasing the tool from frictional engagement with its driving means.

Still another object of the invention is to provide a dental tool of the type described wherein the tool is threadedly engaged with its holding means.

A further object is to provide manually operable means adapted to hold a tool driving member stationary and release a frictional connection between a high speed fluid turbine and a dental tool.

A still further object is to provide a device of the type set forth wherein the manually operable means are completely sealed with respect to the turbine housing.

Other and additional objects and advantages will become apparent to those skilled in the art as the description proceeds in connection with the accompanying drawings, wherein:

Fig. 1 is an enlarged sectional view of a dental drill embodying the present invention; and

Fig. 2 is a view similar to Fig. 1 but showing the parts in different relative positions.

The improvement of the present invention is shown, by way of examples, as applied to a high speed fluid driven turbine device which may be employed to drive dental drills or other dental tools. A hollow handle 2 is provided with a hollow enlargement 4 at .one end thereof defining a housing for the turbine. A nozzle 5 directs fluid under pressure toward the turbine blades and spent fluid returns in hollow handle 2. The turbine comprises a rotor shaft portion 6 having turbine blades 8 fixed thereon. The shaft portion 6 is journalled in bearings 10 and 12, held in the housing 4 by

suitable fittings

14 and 16 threaded into opposite sides of the housing 4. The bearings 10 and 12 are open-ended and the rotor shaft 6 projects from opposite ends of the housing 4, as shown.

The rotor shaft 6 is provided with a central axial bore 18 therethrough and the bore 18 is formed at one end with an outwardly diverging conical surface 20. Axially slidable within the bore 18 is a holding member 22. The member 22 fits bore 18 fairly snugly but is freely slidable therein in an axial direction and is provided with an internally threaded bore 24 from the end thereof adjacent the flared surface 20. The holding member 22 extends outwardly of the bore 18 from the end opposite the flared portion 20 and is provided with an integral enlarged head 26 joined to the body portion by a reduced neck 28. A rubber or the like O-ring 30 surrounds the neck 28 and bears against the under surface of head 26 and the left end of rotor shaft 6. Thus, the O-ring 30 resiliently urges the holding member 22 toward the left as seen in Fig. 1, at least to the position shown in that figure.

The fitting 16 extends outwardly of the bearing 12 and is provided with an internal circumferential groove 32. A cap-shaped resilient diaphragm 34 of rubber or similar material is provided with a peripheral flange 36 extending into the groove 32. As shown, the cap diaphragm 34 extends over and covers the head 26 and its flange 36 constitutes a sealing means whereby the space within the cap 34 is effectively sealed from the exterior of the turbine housing.

The structure thus far described is adapted to hold a dental tool indicated generally at 38, which may be provided with any suitable cutting burr, abrading wheel, brush, or the like. The tool 38 is provided with a shank having a threaded end portion 40 adapted to be threadedly engaged in the threaded bore 24 of holding member 22. The tool shank is also provided with a tapered conical surface 42 complementary to the flared portion 20 of bore 18 whereby to frictionally engage the portion 20 to be frictionally driven thereby.

Assuming that a tool 38 is mounted in the device, as illustrated in Fig. 1, it will be obvious that resilience of the O-ring 30 firmly holds the tapered surface 42 in frictional driving engagement with the flared portion 20 of bore 18 and thus rotation of the turbine shaft 6 effects rotation of the tool 38 therewith. When it is desired to remove the tool 38, pressure is applied to the outer surface of the cap diaphragm 34, as indicated by the arrow A of Fig. 2. While the cap diaphragm 34 is shown in Fig. l as being normally spaced from the head 26, when pressure is applied thereto as indicated in Fig. 2, the cap diaphragm is distorted and depressed into frictional engagement with the outer surface of the head 26. Continued inward pressure on the diaphragm 34 forces the head 26, neck 28, holding member 22, and tool 38 to the right while compressing O-ring 30 in the manner shown. Movement of the parts to the right as described and as shown in Fig. 2, results in disengage ment of the tapered surface 42 of tool 38 from the flared surface 20 of bore 18 and the tool 38 is thus free from driving engagement with the shaft 6. In this condition the tool may be manually grasped and unscrewed from the threaded bore 24. At the same time it is to be noted that the diaphragm 34, being secured to the tur-. bine housing, does not rotate and frictionally engages head 26 to hold the latter and holding member 22 against rotation. By thus holding member 22 against rotation, the tool 38 may be easily unscrewed from the holding member while merely applying pressure to the diaphragm 34 and without the use of any special holding tools. Obviously the procedure may be reversed in mounting a tool 38 on the turbine. When it is desired to mount a tool it is only necessary to depress diaphragm 34 to the position of Fig. 2, whereupon 'a tool 38 may be threaded into holding member 22 until its tapered surface closely approaches the flared portion 20 of rotor shaft 6. Then, upon release of diaphragm 34, O-ring 30 urges the part to the left and to the position of Fig. 1 wherein the tapered surface 42 is held in firm frictional driving engagement with the flared end of the bore 18.

The bearings and 12 necessarily support the turbine rotor rather loosely and some fluid leakage may occur past those bearings. The cap diaphragm 34 prevents any fluid leaking past the bearing 12 from escaping to the exterior of the apparatus. Likewise, O-ring 30 sealingly engages the inner surface of head 26 and the end face of rotor shaft 6 to thereby seal the bore 18 against entry of any fluid leaking past the bearing 12. Turbines of the type described are often driven by water under pressure and if such water were to leak past bearing 12 and enter the clearance between holding member 22 and bore 18, corrosion or other fouling could occur which would hamper the intended mode of operation of the tool holding means. Thus, O-ring 30 performs a dual function.

While a single specific embodiment of the invention is shown and described herein, it is to be understood that other modifications may be resorted to within the scope of the appended claims.

I claim:

1. In a rotary tool having a housing and a fluid driven turbine rotor therein; said turbine rotor having a shaft journalled in said housing and extending through opposite sides thereof, a bore extending axially through said shaft, one end of said bore being flared outwardly, holding means slidable in said bore for holding an end of a tool, and means resiliently urging said holding means away from said flared end and toward the other end of said bore whereby to frictionally hold a complementary portion of the tool against said flared portion of said bore.

2. A rotary tool as defined in claim 1 wherein a portion of said holding means projects outwardly from the other end of said bore to provide means for manually moving said holding means against the action of said resilient means for releasing said portion of said tool 4 from frictional engagement with said flared portion of said bore.

3. A rotary tool as defined in claim 2 wherein said holding means is provided with a threaded portion for threadedly holding said end of said tool, and a resilient diaphragm secured to said housing and overlying said projecting end of said holding means whereby axially inward manual pressure on said diaphragm moves said holding means to release said tool from said frictional engagement and also holds said holding means against rotation relative to said housing for unscrewing said tool therefrom.

4. In a rotary tool having a housing and a fluid driven turbine rotor therein; said turbine rotor having portions journalled in said housing and extending through opposite sides thereof, means carried by one of said portions for threadedly receiving and holding a tool to project from one end of said rotor, and axially movable friction means secured to said housing and overlying the other of said portions in normally spaced relation thereto whereby axially inward manual pressure on said friction means moves the same into frictional engagement with said other portion to thereby hold said rotor against rotation.

5. A rotary tool as defined in claim 4 wherein said friction means comprises a resilient cap overlying said other portion and sealingly secured to said housing throughout its periphery.

6. In a rotary tool having a housing and a fluid driven turbine rotor therein; said turbine rotor having a shaft journalled in said housing and extending through opposite sides thereof, a bore extending axially through said shaft, one end of said bore being flared outwardly, a holding member slidable in said bore and having a threaded portion adjacent said flared end for threadedly engaging an end of a tool, said holding member projecting outwardly of the other end of said bore and having a radially enlarged head thereon, and resilient means between said head and the adjacent end of said shaft urging said member outwardly of said other end of said bore whereby to releasably hold a portion of the tool in firm frictional engagement with said flared portion of said bore.

7. A rotary tool as defined in claim 6 wherein said resilient means is an O-ring surrounding said member inwardly of said head and sealingly engaging said head and shaft.

8. A rotary tool as defined in claim 6 including a resilient cap-like diaphragm secured to said housing and overlying said head in normally spaced relation thereto but manually depressable to engage said head and move said member inwardly of said bore while frictionally holding said member against rotation.

References Cited in the file of this patent UNITED STATES PATENTS