US 2592641 A
Description (OCR text may contain errors)
April 15, 1952 E. BALDERSTONE JOINT STRUCTURE FOR PIVOTED TOOLS Filed Dec. 29, ,1945
FIG I- FIG: 2
3twentor Edward fiaklegwion e Gttorneg Patented Apr. 15, 1952 2,592,641" JOINT STRUCTURE FOR. rrvo'rnn TOOLS Edward Balderstone, Oakford, Pa., assignor to The S. S. White Dental Manufacturing Company, a corporation of Pennsylvania Application December 29, 1945, Serial No. 637,861
My invention relates particularly to that class of forceps that'are adapted tobe employed by dental practitioners in the extraction of teeth, and is especially directed to the pivotal joint structure connecting the opposed jaw members of such implements.
It is well known that several types of pivotal joints have been employed in the manufacture of such forceps or pliers, including the box joint, the knuckle joint and the so called scissor type joint. The box joint has heretofore been preferred for dental and surgical purposes for-the reason that it is deemed to have superior strength and that it was susceptible of being finished to a rounded or oval cross section without introducing any objectionable characteristics. It is obvious that the oval joint structure is, superior because of its freedom from projecting edges its minimum bulk and its consequent smoothness to the feel of the hand of the operator.
It has been known that properly designed forfixed position such, for instance, as when normally closed.
The principal objects ofmy invention are to provide scissors type pliers with the joint structure having a rounded or oval configuration, and
having a-pintle whose head terminates short of the outer oval surface of the relatively movable jaw member.
Other objects of my invention are to provide forceps of the type contemplated in which its pintle is rigidly engaged with one of the relatively movable jaw members, while its retaining head rotatably terminates within the other of said jaw members, and is covered by a plate or cap formed in integral relation with said jaw member and conforming with the oval or rounded surface of said jaw member in which said head is disposed.
Further objects of my invention are to provide forceps or like implements having relatively movable jaw members joined by a pintle, one of said jaw members being provided with a cylindrical orifice having a ledge affording a seat, the other of said jaw members having a conoidal orifice provided with indentations, a pintle extended through said orifices and having a head rotatably 2 Claims. (01. 32-452) engaged with said seat while its free ail-east] is upset or riveted to integrally'engage the indented walls of said conoidal orifice.
Specifically stated, the form of my invention as hereinafter described comprises forceps having relatively movable jaw members each includinga handle and a beak, and being joined pivotally together by a pintle and affording a jointed region whose outer surfaces are rounded, each jaw member of said pliers being provided with a relatively registering aperture, one having a conoidal recess which includes indentations, and the other having a cylindricalrecess affording a' circular seat and a counter recessarranged to receive .a plate or cap, a pintle initially comprising a cyflindrical shank which is arranged tobeextended through said apertures and an enlarged head fitted in said cylindrical recess while ;the free end region of said shank is upset to fill said. conoidal recess, and a cap initially having an upper conical surface and a lower re-entrant My invention'also includes all of the jva rious:
novel features of construction and arrangement as hereinafter more definitely specified.
In'the accompanying drawings, Figure 11 13TH) plan view of a pair of dental forceps=conveniently-embodying myinventi'on; Fig. 2 isafside elevational view of the forceps illustrated in :Fig; 1; Fig. '3 is anenlargedtransverse vertical ','sec.
tional view taken through the joint of the pliers;
in the axial plane of the pintle, as indicated by the section line 3- -3 in Fig. 1; Fig. 4' is a perspective view illustrating the initial formation of the headed pintle which is shown expanded in Fig. 3; Fig. 5 is a plan view illustrating the initial formation of the pintle head cover or cap shown in Figs. 1 and 3; Fig. 6 is a transverse vertical sectional view of the cap shown in Fig. 5, taken axially therethrough on the line 6-$ in said Fig. 5; and Fig. 7 is a fragmentary inverted plan view of the under jaw member of the forceps showing the indentations in the conical wall of the pivotal aperture extending therethrough.
In said figures the forceps illustrated comprise the relatively movable jaw members I and 2 pivotally joined together to relatively rock about the axis of the pintle 3. The upper jaw member I, with reference to the illustrations, includes the handle 4 and the beak 5, and the lower jaw member 2 similarly includes the handle 6 and the relatively opposed beak 1.
As illustrated in Fig. 3, the jaw members i and 2 are respectively providedwith the relatively alined apertures 8 and 9 through which the shank of the pintle 3 extends. Said pintle is initially formed as shown in perspective in Fig. 4 and is provided with the head H).
As shown in Fig. 3, the aperture 8 concentrically joins the cylindrical recess [I which affords the ledge or seat 12 against which the under surface of the pintle head ill rests, so that the upper surface of said pintle head It is disposed. well within the body of the upper jaw member I.
Again referring to Fig. 3, the upper jaw member I is also provided with the counter recess I3 preferably having the retaining undercut or groove 14 into which the closure cap [5, initially formed as shown in Figs. and 6, may be forced and thus caused to assume the form illustrated in Fig. 3 to provide a convenient closure integralwith the jaw member I, for the head it! of the pintle 3.
Referring further to Fig. 3, the pintle aperture 9 in the lower jaw'member 2, concentrically joins the conoidal recess 15 which, as illustrated in Fig. 7, includes a circularly arranged series of angular indentations l1 disposed in relatively angular axial planes in the conical wall of said recess I9 and which may preferably extend into the cylindrical wall of said pintle aperture 9, as shown in dotted lines in Fig. 3.
It will be obvious that the lower region of the shank of the pintle 3, shown in Fig. 4, will, when entered through the apertures Band 9 and sub jected to high pressure or riveting action, con:
form to the conoidal recess I6 and its indentations i! into integral relation with the lower jaw member 2. a
It has been found in practice that the initial form of the cap [5 may preferably be formed cylindrical with its upwardly extending conical surface 18 and its lower inwardly extending conical surface 19 substantially conforming,
, whereby to facilitate the conformation under high pressure of said cap, IE to form the closure forthe head lfl'of the pintle 3,:in integral rela tion with the upper jaw member I.
My invention is advantageous in that, by censtructing the forceps or pliers in the manner herein specifically described, which includes the forming the pintle integral with one jaw mem- ,7
a r 4 when the plier beaks 5 and I are separated to assume an open position.
I do not desire to limit my invention to the 'members, having their outer surfaces convexed transversely, one having an aperture provided with a recess affording a pivot engaging shoulder, and a counter recess providing a circular undercut groove, the other having a relatively alined aperture joining a conical recess having' indentations, a headed pintle extended through said alined apertures, having its head disposed in said first mentioned recess and engaging said shoulder, and having its opposite end ,region expanded to conform to said conical recess and indentations, and a closure for said head engaging said groove and conforming to the curvature of theouter'surface of said implement.
2. An implement of the class described, com.- prising apair of opposed jaw members having their outer surfaces rounded transversely and being relatively movable about a common axis, a headed pintle extended through alined apertures therein, one having a recess affording 'a retaining shoulder for relative rotation of the head of said pintle, and the other having a tapered recess into which the opposite end region ofsaid'pintle is expanded into rigid non-rotating relation therewith, and a cover for the head of 'saidpintle, conforming to the curvature of the outer surface of'said implement; and tightly expanded radially into non-rotatable engagement with the walls of said recess, but rotatable with respect to the head of said pintle. I I EDWARD BALDERSTONE- REFERENCES crrnir The following references are of record in the file of th s p te t:
UNITED STATES PATENTS.