US2489714A - Mechanical pencil - Google Patents

Description

Nov. 29,4 1949 R. J. LYNN MECHANICAL PENCIL 2 Sheets-Sheet l Filed Deo. 20, 1946 R. '.J. LYNN MECHANICAL PENCIL Nov. 29, 1949 2 Sheets-Sheet 2 Filed Dec. 20, 1946 Patented Nov. 29, 1949 UNITED STATES vPATENT OFFICE MECHANICAL PENCIL Robert J. Lynn, Chicago, Ill.

V(Application December 20, 1946, Serial No. 717,413

(Cl. 1Z0- 18) 15 Claims.

My invention relates to a mechanical pencil having a hollow body through which a lead may from time to time be propelled into position for Writing, and more particularly to the propelling unit itself and the means whereby its parts may be readily disassembled for purposes of repair, replacement or otherwise.

In a pencil of this general character, I have incorporated certain improvements which conduce to simplicity of construction, and dependability in operation. For this purpose I associate with the body of the pencil a rotatable tip which induces travel of a propeller by which an active lead is expelled through the tip end of the pencil. The construction of the tip, its connection with the pencil body, and assembly of parts which constitute the propelling unit, present certain improved features with which my invention is mainly concerned.

In the accompanying drawings are shown certain suggestive embodiments of my invention in the manner following:

Fig, 1 is a view in central longitudinal section through the pencil in its entirety;

Fig. 2 is a similar view of the propelling unit which includes an associated tip for the pencil;

Fig. 3 is a transverse section, taken on line'3-3 of Fig. 2;

Fig. 4 is a View in elevation of the propeller per se;

Figs. 5, 6, and 'l are transverse sections taken, respectively, on lines 5-5, 6 6, and 1--1 of Fig. l;

Fig. 8, which is a View generally similar to Fig. 1, shows a modified construction of the pencil and its propelling unit;

Fig. 9 is a similar view of the propelling unit shown in Fig. 8, together with the tip associated therewith;

Fig. 10 is an elevational View of the lead guide to be used with the construction of Figs. 8 and 9;

Fig. 11 is a view in transverse section, taken on line lI-II of Fig. 8;

Fig. 12, which is a View similar to Fig. 9, shows a modied construction of the propelling unit and of the tip associated therewith;

Fig. 13 is a transverse section, taken on line |3-I3 of Fig. 12;

Fig. 14, which is a View similar to Fig. l2, shows a further modication in the construction of the propelling unit; and

Fig. 15, which is a similar View, shows the lead guide tube partially disassembled from the propelling unit of Fig. 14.

The pencil in each of the forms illustrated comprises a body A having at one end thereof a r0- tatable tip B forming part oi a propelling unit whereby to advance an active lead Z through the pencil into ywriting position. At the opposite body end which is open is tted an eraser unit C which provides a closure therefor.

The body A is desirably formed of a composition material which may be molded to shape with the aid of heat and pressure. It is formed in the general shape of a barrel having inner and outer cylindrical walls 35 and 36 defining between them an annular magazine m. An end wall 31 closes the axial chamber c defined by the inner wall 35. At its opposite end the inner wall is joined to a supporting base .38 from which is axially extended a nose 4l] of smaller diameter having a cylindrical section 4l beyond which the nose is tapered down at 42. Throughout the nose and rbase the axial chamber c is continued in the same diameter as elsewhere.

To a body A of the general kind under description is tted the rotatable tip B which, together with the parts carried thereby, constitutes the propelling unit. As shown, this tip is of two parts, comprising an upper tapered section 45 having its wallsv 46 at the point of maximum diameter straightened out into cylindrical form for frictional engagement with the corresponding wall 4| of the nose. This tapered section is adapted, therefore, to be intertted with the lower end of the body, and to be rotated relative thereto while retained frictionally in assembled relation therewith. The tip comprises also a terminal section 50, desirably of metal, which is joined to the tapered section 45 at its smaller end so as to constitute a continuation thereof. At lts extremity, the terminal section is slit longitudinally at a plurality of places 5I to provide segmental spring jaws with capacity for gripping between them the lead Z which is to be advanced longitudinally therethrough.

Both sections 0f the tip are formed interiorly -with an axial passageway having a diameter slightly smaller than that of the axial chamber c lwithin the inner walls 35 of the lbody. Into this :passageway is inserted a coupling in the form of Aa tube 55 having near vits lower end a slightly enlarged head 56 whereon is formed a plurality of helical threads. The lower end of this coupling tube terminates ,short of :the corresponding end of the axial passageway. This head 56 is adapted to :be rotatively forced through the passageway into the terminal section of the tip, and in the process to form therein threads corresponding to its own helical threads Iwhereby to eiiect a press-fitted connection therewith. The head of the coupling tube thus engaged with the terminal section of 'the tip is wholly accommodated therewithin so as to lie just beyond the upper tapered section of the tip.

Within the tapered section of the tip, near its smaller end, is a keyway for receiving a boss 6l that is projected radially from the coupling tube. When entered within the keyway, the boss is advanced to the inner end thereof into abutting relation therewith. The tapered tip section is accordingly locked non-rotatably to the coupling tube. The coupling and tapered section of the :tip are rotatable together during the oper- I provide in the coupling tube one or more longitudinali slits Sd which conned to 4the regionadjacent thef nose 40 in the lower end of the body. Between these slits the walls of the tube are bowed outwardly (see Fig. 2) in the form of springY sections which are adapted to engage resiliently with the surrounding Iwalls of the body nose. A frictiona-l, yet separable, connection is thereby provided' between the .body and tip through the mediumof .the coupling tube.

Mounted within the coupling tube so as to extend for the full. length thereof and beyond, is a lead guidetube 'lil' which, as shown in Figs. 1 and 2,. may consistjo'f.' a il'atmetallic ribbon which is rolled intotubular form with an intervening helical slot '1| which is continuous from end to end'. The lowerY end of. this guide tube 'it projects beyond the corresponding end of the coupling :tube 55 so as 'to be accommodated within the bottom end of :the axial passageway. The opposite end of the guide tube which remains pro- -truded beyond the coupling tube may be knurled at T2' to facilitate its manual operation whenever Jthe tube is to` be'a'ssernbledi or disassembled relative to the coupling tube'55. For assembly, the

lead guide tube l0 is advanced inwardly to the I4 `into and. `within the bayonet slot 16, and is then rotated-"sufficiently to shift the boss laterally -i'nto' the tail endthereof. When so positioned, the guidel tube', then slightly under compression, vwill remain i'ixedly and 'immovably assembled 'with thel coupling tube so as to be handled as a unit therewith. Normally theone is not separable "from the othen'but in the event of any clogging 'within the:v guide tuba'the latter may be removed from the coupling tube to facilitate a cleaning .out operation', or replacement, or repair, according to the condition that exists. Formed for cooperation with the" guide tube is "a propeller 'En which may comprise a relatively inflexible wire having atits trailing end a flattened head 8|, 'andnear its. leading end a tooth 182 which maybe extended helically laround the wire for perhaps 360. This'tooth is adapted to enterthe' helical slot "H oi the. guide tube and, when rotated-.relativethereto,'to induce a longitudinal travel ofthe propellertherewithin. The

flattened head of the propeller is received within the axial chamber c of the body. This chamber is of non-round cross section, being formed lwith one or more longitudinal grooves 83 (see Fig. 7) wherein the propeller head 8| is freely slidable while held against rotation.

The annular magazine m between the inner and outer body ywalls 35 and 36 is adapted to accommodate reserve leads Z (see Fig. 6) which may be admitted thereintoor withdrawn therefrom only when the eraser unit c is removed from the upper end of the pencil. By this arrangement, I provide a suiiicient space, readily accessible yet normally closed off, for a supply of reserve leads which Vwill enable the user of the pencil to employ it continuously over an extended .period of time.

It `will be obvious that the .propelling unit which l's. have described serves certain very useful and manifold purposes. The two sections of the tip are interconnected bythe coupling tube of the unit which also provides a frictional, yet removable, connection between the tip and body ,permitting the one to be rotated relative tothe other. Also, by the special means by which the lead guide tube is locked within the coupling tube, the former is maintainedfin -a state of compression, so as to rem-ain` immovable longitudinally while operating to advance theV propeller lengthwise of itself, thereby to push the active lead l into writing position.

Coming now to Figs. Bell, this form of pencil utilizes a body A and a tip B which isrltted thereto ior'rotation thereupon. In this case the body is chambered to receive av tube 85 having a nonround crossvsectional form, as best shown in Fig. l1, which may provide opposed grooves 86 within opposite ones of which. is slidably received the attened head 8l of a wire propeller 88. This tube is supported. throughout its lower end region by the bod-y walls which arev extended inwardly to establish engagement therewith.

The propelling unit comprises a metallic tip Si] which is suitably tapered to cooperate with the tapered. lower end of the body with which it engages, the extremity of the tip being. slitted longitudinally at 9 i in aplurality of places to provide spring jaws between which the active lead Z is frictionally gripped. This tip is provided with an axial passageway wherein is an annular shoulder 5, this passageway for a distance being of uniform diameter so that its wallsmay engage a head at the lower end of a coupling tube when tted thereinto. This. tube may be rotatively press-fitted to its nal. position of rest against the shoulder 95, and in so doing the helical. threads which project from its head. 96 will form in the surrounding walls of the tip like threads which coact to provide a xed and inseparable connec tion between theseparts.

The coupling tube is also slitted lengthwise as at itil at onev or more places to prov-ide a plurality of resilient sections which are normally bowed outwardly (see Fig. 9). When the tip, together with its assembled coupling tube, is tted to the end of the pencilbody, these bowed spring sections engage frictionally with the tube 35, and in so doing are flattened somewhat (see Fig. 8), thereby acting to' provide the desired degree of friction for maintaining these parts against normal separation while permitting free rotation of one relative to the other.

With a-tip having a coupling tube of the kind described, I associate a lead. guide tube here shown as an open wire coil I 02 from which is projected, near its lower end, a boss |03 and a second boss |04 near its upper end. The lower boss is adapted to be sprung outwardly into a slot |05 which is formed transversely of the coupling tube and, when fitted therewithin, will hold that end of the guide tube fixedly with respect to the supporting tube within which it is accommodated. The boss |04 near the upper end is adapted to enter a bayonet slot |06 at the upper end of the coupling tube 91 and, in response to compression of the coil tube to advance longitudinally, then laterally, thereof into a reversely turned tail end as shown in Fig. 9. The guide tube is thus maintained slightly under compression so long as its assembly with the coupling tube continues, and relative movement between the two tubes is effectively prevented in consequence. The propeller 88 is formed with a helical tooth |08 adapted to travel between the coils of the guide tube, and in so doing to advance the propeller endwise of itself. This motion is imparted whenever the tip is rotated relative to the body, the latter then holding the propeller against rotation. By this simple form of mechanism the active lead l is driven forwardly so that successive portions of its extremity may be exposed for writing beyond the tip end of the pencil.

.In Figs. 12 and 13 I have shown a slightly modified form of propelling unit in which the tip B comprises a tapered section H0, desirably of a composition material, and a terminal section of metal having slits ||2 at its extremity to provide spring jaws between which an active lead Z may be frictionally gripped. In this construction, the axial passageway through the metallic section of the tip is interiorly threaded at ||5 to engage with the threaded lower end of a metallic coupling tube when fitted thereinto. This passageway continues through the tapered section ||0 where radially opposite slots ||8 end in shoulders ||9 at the lower end. The coupling tube is provided with a pair of oppositely extending wings adapted to enter into the slots ||8 and rest against the shoulders ||9 at the` lower ends thereof. By reason of this interengagement, the coupling tube ||1 is locked against rotation relative to the tapered section 0 so that the latter, when rotated relative to the terminal section will cause the coupling tube to be rotatively position relative thereto. tip sections may be tightly secured together through the instrumentality of the coupling tube l At its upper endthe coupling tube is constricted to provide a neck which is interiorly threaded for cooperation with the external threads |26 of a wire propeller |21 having a attened head |28 near its upper end. This head is adapted to be held non-rotatably, yet slidably, within a pencil body having a non-round axial chamber with one or more longitudinal grooves of the general kind already described in connection with Figs. 7-11. Manifestly rotation of the propelling unit relative to the body will cause the propeller to be advanced lengthwise of itself whereby to push an active lead Z outwardly as far as desired.

In Figs. 14 and 15 I have shown a still further modification of the propelling unit which comadvanced to its final In this way the two CFI prises a one-piece tip |30, desirably of metal, with y70 longitudinal slits |3| at its extremity to dene spring jaws between which an active lead l may be advanced. In this case the coupling tube is provided near its lower end with a slightly enlarged head |36 having helical threads of high pitch-adapted, in response to a forced rotative advance of the tube, to cut grooves inthe surrounding cylindrical walls of the tip, thereby to secure the one immovably to the other. The lower end of this coupling tube stops short of the end of the passageway which is extended axially through the tip, as shown in Fig. 14.

- The upper end of the coupling tube is adapted to receive thereinthe inset Walls |40 of a sleeve having a shoulder |4| adapted to abut the upper end of the tube when assembled therewith. This sleeve is formed at its lower end with a relatively wide but shallow helical groove |45, extending circumferentially for one or more turns, for receiving therein an interrupted internal thread |46 (see Fig. 15) which is projected inwardly from the vsurrounding coupling tube. By this thread and groove interengagement the sleeve may be advanced rotatively to its nal position which is shown in Fig. 14; the sleeve then serving as an extension of the coupling tube. The outer end of the sleeve is desirably knurled at |48 to facilitate theseV manual operations.

' Extending within the coupling tube and the sleevel walls |40 is a lead guide tube |50 here shown as a wire formed into coils which are spaced from each other to provide therebetween a continuous helical slot. The lower end of this wire coil extends beyond the corresponding end of-the coupling tube so'as to abut against the taperingV lower end of thelaxial passageway of the tip. rThroughout the ylength of the coupling tube, the i-lt of the wire coilftherewithin is free and loose? but therebeyond, the interior diameter of the sleeve is'slightly less so as to eiect a frictional engagement with the `wire coils at this point. Manifestly, in assembling the coil tube in place, it may be stretched, if necessary, to reduce its diameter at the upperend so as to facilitate its insertion into the sleeve extension; when allowed to resume its normal'state the tube will contract somewhat thereby expanding its coils to effect a tightengagement with the sleeve. In this manner Iv provide for a resilient connection which is normally inseparable and immovable between the guide tube andthe coupling tube through the medium of its Asleeve extension, but one which permits of disassembly, if desired, for purposes of replacement, repair, or otherwise. The propelling unitiscompleted by a wire propeller having a flattened head |55 which is adapted to cooperate with one or more longitudinal grooves in the pencilbody, as per a construction such asis shown in Figs. 7 and 11. The coupling tube v|35 Amay also be slitted as at |58 for av limited distance lengthwise of vitself in the region where it iirst enters the pencil body so as to 'engage frictionally therewith. In this manner the tipis connected to the ybody with capacity for rotation relative thereto. When so assembled, the propeller is restrained from rotary movement but may be advanced longitudinally, in response to turning of the tip relative to the body, whereby to propel ahead-of itself the active lead Z that is projected through the spring jaws at the extremity of the tip. f. 'A feature of importanceto my improved propelling unit is the resilient separable interflt of the coupling and Vguide tubes. The protruding upper kend of the guide tube is readily manipulatable to effect the disassembly operation. Also the utilization of a coupling tube for fixedly interconnecting two parts of a tip in endwise relation is'afurther featurev of importance.I `Such a con.-

S7 ne'ction involves no extra parts lor operations-dt requires only that the coupling tube be rotatively advanced to its iinal position. In this operation there is formed in one of the tip sections the helical threads needed for coaction with the tube in order to establish what I have termed 'a press fit connection therebetween. For all practical purposes such a connection is permanent and inseparable, as it should be. There is the further advantage, from an assembly and operating standpoint, that this fixed connection between the coupling tube and one tip part establishes also a ixed and relatively inseparable connection between the two tip parts so that, in eiect, they become 'a single unit. Here again I have simplied economized upon the procedure necessary for assembly and interconnection of these parts which are comprised in the propelling unit.

I claim:

1. For use with a pencil having a bo'dy wherein is a non-round axial chamber open upon one end, a propelling unit comprising Va tapered tip applicable to the open end of the body, a coupling tube affixed at lone end to the tip and extended axially therefrom into the bo'dy chamber for frictional, yet separable, engagement therewith, the tip and tube being formed with axial passageways in communication with each other and with the axial chamber in the body, a lead guide tube tted within the coupling tube and having one end abutting the tip and the other end protruded beyond the proximate end of the coupling tube, coacting means on the lead guide tube and on the coupling tube at its end remote from the tip for connecting the two tubes fixedly, yet releasably, one to the other, and a propeller in slidable, nonrotatable, engagement with the pencil body extended within the lead guide tube and in screw threaded connection therewith adapted to be advanced therewithin in response to rotary movement of the tip relative to the body.

2. For use with a pencil having a body wherein is a non-pound axial chamber open upon one end, a propelling unit comprising a tapered tip applicable to the open end of the body, a coupling tube aihxed at one end to the tip and extended axially therefrom into the body chamber for frictional and rotatable engagement therewith, Athe tip and tube being formed with axial passagewaysin communication with each other and with the ,y

axial chamber in the body, a lead guide tube fitted within the coupling tube and having one end abutting the tip, coacting means on the lead guide tube and on the coupling tube at its end remote from the tip for connecting the two tubes xedly and releasably one to the other, and a propeller in slidable, non-rotatable, engagement with the pencil body extended within the lead guide tube and in screw threaded connection therewith adapted to be advanced therewithin in response to rotary movement of the tip relative to the body.

3. For use with a pencil having a body wherein is a non-round axial chamber open upon one end,

a propelling unit applicable to the open end of the body and comprising a tip of two parts arranged end to end and formed therethrough with an axial lpassageway communicating with the chamber in the body, and a coupling tube fitted in the passageway of the two tip parts in threaded engagement with the outer part and in abuttingengagement with the inner part and extending therefrom into the axial chamber of the vbody for irictional connection therewith, the coupling A-tube thus serving to fixedly, yet separably, unite the two parts of the tip `and to rotatably and releasably secure the tip to the body.

4. For use with a pencil having a body wherein non-round axial chamber open upon one a propelling unit applicable to the open end of J.ie body and comprising a tip of -two parts arranged end to end and formed therethrough with an axial passageway communicating with the chamber in the body, and a coupling tube fitted the passageway or" the two tip parts in threaded engagement with one vand abutting engagement with the other and extending therefrom into the two parts ol the tip and to rotatably, yet separably, secure the tip to the body.

5. For use with a pencil having a body wherein is a non-round axial chamber open upon one end, a propelling unit applicable to the open end of the body and comprising va tip, a coupling tube afx'ed at one end to the tip and extending axially therefrom into the cody chamber for frictional and rotatable connection therewith, an endwise compress )le lead guide tube fitted within the coupling tube and releasably locked thereto under cor.. res on, and a propeller in screw threaded engage with the lead guide tube and movable long dinaily therewithin in response to rotation oi the tipI relative to the body.

For use with a pencil having a body wherein is a no -round axial chamber open upon one end, a propelling unit applicable to the open end of the body comprising a tip, a coupling tube aiz'cd at one to the tip and extending axially om '--to the body chamber for frictl l i rotatable connection therewith, an axiaily compressible lead guide tube fitted into tube and connected therewith while maintained under compression, and a propeller in screw threaded engagement with the lead guide tube and movable longitudinally therewithin in response to rotation of the tip relative to the body.

y '-7. For use with a pencil having a chambered body open upon one end, a propelling unit attachable to the open end of the body and cornprising a tip of two parts in end to end relation having an axial passageway therethrough, a coupling tube fitted into the tip passageway and extended axially therefrom into the body chambei', raised helical threads on the tube adapted, in response to a forward rotation, to cut like threads in one tube part to establish a fixed connection therewith, and means on the tube in thrust engagement with the other tube part adapted to maintain the same tightly against the rst tube part in unitary relation therewith.

8. A pencil in which is combined an axially chambered body and a tip, one rotatable relative to the other, a pair of tubes one axially compressible and inside the other and separably connected thereto while under endwise tension for concurrent rotation, a rotative pressed nt connection between the outer tube and the tip, and a propeller movable lengthwise through the inner tube in screw threaded connection therewith and in non-rotatable sliding connection with the body.

9. A pencil in which is combined an axially chambered body and a tip, one rotatable relative to the other, a coupling tube in fixed connection at on4 'o and having an outwardly '75 means providing a releasable lock between the two tubes operable by rotative and axial manipulation of the outwardly extended end of the lead guide tube, and a propeller movable through the lead guide tube in screw threaded connection therewith and in non-rotatable sliding connection with the body.

10. A pencil in which is combined an axially chambered body and a tip therefor, a coupling tube connecting the tip to the body for rotation relative thereto, and a propelling mechanism comprising an axially compressible lead guide tube tted within the coupling tube and extended outwardly beyond the upper end thereof, and a boss and bayonet slot connection between the two tubes for Securing them together in unitary relation.

11. A pencil in which is combined an axially chambered body and a tip therefor, a coupling tube connecting the tip to the body for rotation relative thereto, and a propelling mechanism comprising an axially compressible lead guide tube fitted within the coupling tube and extended outwardly beyond the upper end thereof, and a screw-threaded connection between the two tubes for securing them together in unitary relation.

12. A pencil in which is combined an axially chambered body and a tip therefor, a coupling tube frictionally connecting the tip to the body for rotation relative thereto, and a propelling mechanism comprising a lead guide tube fitted loosely within the coupling tube and extended outwardly beyond the upper end thereof, and a screw-threaded connection between the two tubes for securing them together in unitary relation.

13. A pencil in which is combined an axially chambered body and a tip therefor, a coupling tube frictionally connecting the tip to the body for rotation relative thereto, and a propelling mechanism comprising a lead guide tube tted loosely within the coupling tube and extended outwardly beyond the upper end thereof, and means affixed to the upper end of the coupling tube and in engagement with the lead guide tube to confine the latter in a fixed position axially of the coupling tube.

. 14. A pencil in whichI is combined an axially chambered body and a tip therefor, a coupling tube frictionally connecting the tip to the body for rotation relative thereto, and a propelling mechanism comprising a lead guide tube tted loosely within the coupling tube and extended outwardly beyond the upper end thereof, and a sleeve in screw threaded connection with the coupling tube forming an extension therefor at its upper end and provided with means projecting inwardly thereof in engagement with the lead guide tube for confining the latter in a. xed position axially of the coupling tube.

415. For use with a pencil having a body wherein is a non-round axial chamber open upon one end, a propelling unit applicable to the open end of the body and comprising a tip of two parts arranged end to end and formed therethrough with an axial passageway communicating with the chamber in the body, a coupling tube fitted in the passageway of the two tip parts in threaded engagement with the outer part, there being a slot extended radially outwardly from the axial passageway of the inner tip part and extending longitudinally toward its opposite end, a wing extended outwardly from the coupling tube in position to enter the radial slot of the inner tip end and engage with the outer end of the slot to limit the axial advance of the coupling tube within the tip, the coupling tube thus serving to fixedly, yet separably, unite the two parts of the tip and to rotatably and releasably secure the tip to the body.

ROBERT J. LYNN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,659,533 Lynn Feb. 14, 1928 1,943,792 Garvey Jan. 16, 1934 2,356,509 Deli Aug. 22, 1944

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