US 3798776 A
A dental-type handpiece providing for accurate assembly and for easy removal of a tool-clamping collet.
Description (OCR text may contain errors)
United States Patent [.191
Lentine et al.
[ 1 Mar. 26, 1974 1 DENTAL-TYPE HANDPIECE  lnventorsz- Frank Nickolis Lentine, Wayne;
William Henry Boggs, Riverview,
both of Mich.
 Assignee: 'Sybron Corporation, Rochester,
 Filed: Sept. 7, 1971  Appl. No.: 178,195
52 U.S.Cl. ..32/26 51 lm. Cl. ..A6lc1/08  Field ofSearch ..32/26,27
 References Cited UNITED STATES PATENTS 3,631,597 l/l972 Lieb 32/26 3,475,817 11/1969 Loge 312/26 Primary ExaminerRobert Peshock Attorney, Agent, or FirmTheodore B. Roessel; Joseph C. MacKenzie [5 7] ABSTRACT A dental-type handpiece providing for accurate assembly and for easy removal of a tool-clamping collet.
2 Claims, 3 Drawing Figures PATENTEUHmsJsM INVENTORS W. H. 80668 F. N. LENTINE ATTORNEY DENTAL-TYPE IIANDPIECE FIELD OF THE INVENTION This invention relates to dental-type handpieces wherein a hollow spindle has a collet in one end for gripping a burr, or other cutting tool for precision cutting of bone, tooth, or material of similar nature. The collet is held in place by a readily removable C-ring, and the spindle is supported for rotation in a tubular housing.
DESCRIPTION OF THE PRIOR ART In handpieces of the above-described type, spindle and collet are mounted within a tubular housing. The housing has a lever or the like for actuating the collet when it is desired to insert, remove, or change tools, and also provides the means with which the dentist grasps the tool in his hand. The handpiece, though relatively-small and delicate, and a more or less precisiontype mechanism, is nevertheless subject to substantial wear and tear in use. It is therefore rather difficult to construct one that is simultaneously simple, easy to maintain, sturdy, and not overly-costly. Many tend to be put together rather permanently, so that, for example, the dentist is unable to get at the mechanism within the housing, say, to clean it.
SUMMARY'OF THE INVENTION In the present invention, the portion of the housing containing the collet is made removable and the collet is fixed to the hollow spindle by means such as a C-ring, accessible to the dentist, once the said portion of the housing is removed. The spindle is journaled within the housing by a pair of bearings only one of which is fixed to both spindle and housing. The other bearing fits in the housing and is fixed to the shaft, but not to the housing. In this way, assembly of the handpiece when it is manufactured, only requires registration of spindle and housing at one point, and cross-loading on the second bearing is eliminated.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partially-sectioned view of the tool-end of the hand piece of the invention, the sectioning being taken along the long axis of the handpiece, and is to scale but about four times life-size.
FIG. 2 is like FIG. 1, exceptit is a view of the motor end of the hand piece according to the invention.
FIG. 3 is a view such as would be seen upon looking into the handpiece from the left of FIG. 1, and is to the same scale as FIGS. 1 and 2.
In FIG. 1, the handpiece presents to external view, at its tool-end, a tubular housing 1 terminating in a nose cone 2, out of which projects the shank 3 of a suitable tool having a burr orother element (not shown) for working on teeth.
Nose cone 2 is threaded onto housing 1, as indicated at 4. Inside the nose cone is one end of a hollow spindle 5, and inside this one end is a collet 6. Also, within the spindle is a collet operator 7, only part of which is shown in FIG. 1) urges operator 7 toward the left in FIG. I and, due to the slot 10 (one of four equispaced about the circumference of collet 6), squeezes the split portion of the collet against the sides of shank 3, thereby frictionally securing shank 3 in place. This collet and collet-operator structure and functioning is, of course, well known in many forms including the one shown, as thus far described.
Collect 6, which is made of a somewhat springy metal, has an enlarged circularly right cylindrical portion 11 which is slidingly received in spindle 5 and terminates in a circularly right cylindrical flange l2 similarly received 'in spindle 5. The diameter of flange 12 is larger than the diameter of portion 11 which in turn is larger than the diameter of the split portion of the collet. Portion 11 and flange 12 of the collet fit snugly in spindle 5, forming a more or less rigid part thereof in effect.
Flange 12 seats on an annular ledge 13 in spindle 5, and is held in place by a C-ring 14, a suitable annular groove being provided internally of spindle 5, into which groove the ring fits. Flange 12, as part of the collet, fixes the collet in position on the longitudinal axis of the instrument by C-ring l4 and shoulder 13. I
A ball bearing 16 having an outer race 17 and an inner race 18 provides for rotating spindle 5 with respect to housing 1. The inner race 18 is fixed to the spindle by any suitable means for preventing it from sliding along the spindle. As shown, a snap ring 19, in a suitable groove around the spindle, urges therace 18 against a ledge around the spindle on the other side of race 18 from the ring 19.
The outer race 17, however, the outer surface of which is circularly right cylindrical, is closelyfitted but slidably, by a like-shaped land 20 formed on the inner bore of the housing. While the fit need not be loose enough to allow the race 17 to slide easily along the length of the land, neither should it be so snug that the race 17 binds on the land. Further, it is to be noted that a definite clearance is intentionally provided between the threaded end of the nose cone 2 and the adjacent side of land 20. This clearance is assured, in fact, by a flange 21 on nose cone 2, which flange seats on the end of housing 1 in order to prevent the nose cone from being screwed too close to the race17.;As will be seen from FIG. 1, housing 1 includes a middle housing portion 22 and an end using portion 23. As indicated at 24, portion 22 is threaded into portion 23. v
A ball bearing 25 is located between portions 22 and 23, the fit of which provides for locating spindle 5 correctly with respect to housing 1, when assembling the handpiece. Thus, as shown, the outer race of bearing 25 is fitted into the end of portion 22, but projects slightly out of it. At the same time the inner race of the bearing abuts the snap ring 26 which is, received in a suitable annular groove around spindle Ss exterior. To the right of bearing 25 is a spring washer 27 held against the inner race only of the hearing by means of ledge 28 of a groove 28A on spindle 5. A ledge 15 of portion 23 faces the outer race only of bearing 25, which in turn seats on a ledge 29 of housing portion 22. In assembly, the two housing portions are screwed tightly together, thereby rigidly clamping the outer race of bearing 25 between them. At the same time, spring washer 27 prevents spindle 5 from moving to the left,
thereby preserving the clearance between bearing 16 and the adjacent end of nose cone housing portion 2.
Washer 26 is flat and axially incompressible, whereas washer 27 is undulant and split, or otherwise so formed that it has to be compressed axially to seat it in groove 28A after having been sprung open to get it on the spin dle to a position over the groove 28A. As groove 28A extends to the left slightly under the bearing 25, the force due to the compression of the washer jams the bearing solidly against washer 26 which, for all intents and purposes, is a rigid part of spindle 5.
In manufacturing the parts, then, the fit between housing I and spindle 5 is controlled solely by fixed points on spindle 5 and on portion 22, namely, ledge 29 and ring 26, independently of the threaded engagements at 4 and 24. In other words, the parts inherently fit correctly together, and no adjustments are required for dimensional variation of the separate parts.
The function of operator 7 requires it to slide along the spindle, so it is provided with circularly right cylindrical enlarged portions 30 and 31, allowing it to fit fairly closely yet slidable within the spindle 5, while neither cocking or binding.
In FIG. 2, a spring 32 prov-ides for making the flared end of bore 8 squeeze the parts of the slotted end of the collet 6 together. To withdraw the shank 3, it is necessary to force the operator 7 to the right, in order to allow the slotted end to open up, due to the springiness of the material from which it is made, and release shank 3. Any suitable means may be provided for this. Typically, such means will take the form of a handle 33 which when deflected clockwise, shifts a ring 34 along the hollow spindle 5. There are slots 35 through the top and bottom of the spindle through which a pin 36 passes. The middle part of pin 36 is fixed to the operator 7, and its ends are fixed to the ring. Accordingly, if the ring is shifted to the right from the position shown slots 35 will permit it to pull the operator 7 off collet 6. The spring32 is always in compression in spindle 5 between the right hand end of the operator 7 and a seat 37 at the end of the spindle. Hence, when the handle 33 is deflected clockwise, spring 32 is further compressed, and when the handle is released, the force stored in the spring forces operator 7 back to the position shown.
Handle 33 is pivoted to housing portion 23, as indicated at 38, and a set screw 39 threaded therein projects from the underside of the handle against an arm 40 projecting from a fork having a pair of arms 41 (only one is visible in FIG. 2) straddling spindle 5. The fork is pivoted to housing portion 23, as indicated at 42, so if the handle is deflected clockwise, the fork is deflected anti-clockwise, whereby arms 41 push ring 34 to the right, as aforesaid. A leaf spring 43, connected at one end to handle 33, and having its other end bearing on an arm 44 of the fork, biases the arm 40 into engagement with set screw 39 and holds the lever 33 and fork arms 41 in the position shown except when the lever is being deflected. The lever is deflected, of course, by the operator's hand. Housing portion 23 is cut away as indicated at 48, to accommodate the fork and the motions of its arms 40 and 44.
Housing portion23 provides for connecting a motor, or other rotary driving device, at its end, which is open to allow access to the driven end of spindle 5, which is formed as a clutch element, chuck, or any other suitable means for engaging the driving element.
As shown, spindle 5 has a flare 45 for fitting a tapered motor coupling (not shown).
In use, it is desirable to be able to get at the collet 6 for cleaning it. To do this, nose cone 2 is unscrewed, thereby presenting the view of FIG. 3 (from which has been eliminated, however, those parts of the handpiece corresponding to FIG. 2). Then, using the usual C-ring removing tool, the apertured ears 46 of C-ring 14 are squeezed together to free it from its internal groove in spindle 5. As at this point, there would be no tool in the collet, and it can be freed from spindle 5 by depressing handle 35 to cause operator to move to the right to the position showing without, however, making pin 36 contact the ends of slots 35. Under these conditions, the collet is easily slipped out of the spindle 5.
Bearing 25 is the main bearing of spindle 5 and, since the front bearing 16 floats, so to speak, that is, can slide axially of the housing 1 on land 20, bearing 25 absorbs all the cross loading that arises during use of the hand piece. It is therefore chosen to be sufficiently sturdy and large to suit these functions. Bearing 16, on the other hand, needs to be substantially nothing more than a substantially frictionless guide for eliminating wobbling of spindle, due to such play as bearing 25 may permit. Hearing 25 thus forms the sole means for fixing the spindle 5 in place in housing 1.
Preferably, the threaded fit at 24 is frozen by treating the threads with a suitable substance, such as Loctite, so called, or by other expedients which will prevent loosening of the housing portion 22 from housing 22, as a result of vibration, use, or casual tampering. Such expedient is not applied to threading at 4 since it is desirable, as pointed out above, to allow the dentist to remove nose cone 2, and, moreover, it is unneces-. sary to fix the nose cone so permanently in place, because its loosening or removal will not disturb the working relationship of the moving parts of the hand piece.
Certain modifications of the hand piece mechanism will be obvious. For instance, bearing 16 could be arranged to be fixed to housing portion 22 and to float on the spindle. Again, expedients other than threading could be used to hold the housing portion together. However, whatever the expedient or expedients used, preferably the engagement of portions 22 and 23 are relatively permanent, whereas that between nose cone 2 and housing portion 22 must be such as to allow easy removal of the nose cone from portion 22.
Again, devices other than C-rings can be used to hold the collet in place in spindle 5, but are preferably not of a kind in the nature of bolts, nuts or other threaded elements, which unlike the C-ring 14 are neither inherently adapted to being readily removable, nor at the same time proof against loosening due to vibration.
Finally, tool gripping elements other than collets can' be used on the spindle 5, provided they are readily removable, as by removing C-ring 14 or the equivalent.
Having thus described our invention in accordance with the statutes, we claim:
1. A dental-type instrument having a hollow-ended driving spindle and a collet within such hollow-end; said collet being fixed to said spindle, there being readily-releasable means cooperating with said spindle and said collet for'normally maintaining said collet in fixed relation to said spindle, said readily-releasable means, when released, being adapted to allow removal of said collet from said hollow-end;
6 said collet and said spindle being adapted to receive tween said abutment and said readily-releasable a portion of a tool for driving said tool by means of means; Said Spindle while said collet clamps Said tool in said releasable means being a C-ring substantially place, and said spindle having collet-operating means manually operable to alternately open and 5 close said collet for, respectively, removing or insertin such tool in said sleeve, and fixin such tool in paie in Said Spindle; g 2. The dental-type instrument of claim 1, wherein Said hollowend having an intern? abutment Sup said collet-operating means includes a collet-operator, rounding Said collet, Said collet having fl g 10 and a spring urging said operator against said collet and means substantially seated on said abutment, and sand flange means agamst 531d g slmultaneouslyv said readily releasable means contacting said spinr operating aid c llet to clamp Said tOOl. dle and said collet for fixing said flange means beabutting said flange means and received in an internal groove in said hollow-end, said flange means being between said C-ring and said abutment.