US2818045A - Mechanical pencil feed mechanism - Google Patents

Description

Dec. 31, 1957 B. D. sMlTH 2,818,045

' MECHANICAL PENCIL FEED MECHANISM Filed Oct. 25, 1956 2 Sheets-Sheet 1 Figui lmig 23A 26 By A BLANcn/mqa swr" A fron/v5 Ys JNVENToR.

I Dec. 31,1957 B. D. sMrrH MECHANICAL PENCL FEED MECHANISM Filed Oct. 25, 1956 2 Sheets-Sheet 2 .Il I ll lll -iza 7* yl Fi g. .134'

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- /.A/vc/mnon, s/wm/ 6F/f 21 C g sa lUnited States Patent MECHANICAL PENCIL FEED MECHANISM Blanchard D. Smith, Atlanta, Ga., assignor to Scripto, Inc., a corporation of Georgia Application October 25, 1956Serial No. 618,224

10 Claims. (Cl. 1Z0- 18) This invention relates generally to mechanical pencils of the type incorporating a propelling member for controlling the feeding of a writing lead, and-more particularly to an improved feed mechanism for such pencils in which only a spiral feed member rotates relative to the other feed mechanism elements during operation thereof; n

These and other features of the present invention are described in detail below in connection with the accompanying drawings, in which:

Fig. 1 is a side elevational View, mainly in longitudinal section, of a mechanical pencil embodying the present invention;

Fig. 2 is an enlarged fragmentary detail in longitudinal section of the writing end of the pencil shown in Fig. l;

Fig. 3 is an enlarged fragmentary detail, in longitudinal section, of the rear end portion of the feed mechanism shown in Fig. 1;

Fig. 4 is a transverse sectional detail taken substantially at the line 4 4 in Fig. 3;

Fig. 5 is a vertical section of the thrust washer `sh-own in Figs. 3 and 4'as seen substantially on the line -5-5 in Fig. 4;

Fig. 6 is a transverse sectional detail, with surrounding parts omitted, taken substantially `at the line 6-6 in Fig. 3;

Fig. 7 is an enlarged fragmentary detail corresponding generally with Fig. 2 but kshowing the disposition of the propelling member after separate m-ovement with respect to the clutch member for ejecting a spent lead therefrom and partly in quarter section to show the spare lead compartment provided;

Fig. 8 is an enlarged fragmentary transverse sectional detail taken substantially on the line 8 8 in Fig. 7;

Fig. 9 is an enlarged fragmentary transverse sectional detail taken substantially on the line 9-9 in Fig. 7;

Fig. 10 is an enlarged detail in elevation of the lead propelling member;

Fig. 1l is a corresponding elevation detail as seen from the right in Fig. 10;

Fig. 12 is a top plan detail corresponding to Fig. 10;

Fig. 13 is a sectional detail taken substantially at the line 13-13 in Fig. 10;

Fig. 14 is a sectional detail taken substantially at `the line 14-14 in Fig. 10;

Fig. 15 is a sectional .detail taken vsubstantially at the line 15-15 in Fig. I10;

Fig. 16 is a sectional detail taken substantially at the line -16-16 in Fig. 10;

2,818,045 Patented Dec. 31, 1957 ICC Fig. 17 is an enlarged detail in .elevation of the `lead clutch member;

Fig. .18 is a corresponding elevation detail vas seen from the right in Fig. 17;

Fig. 19 is a bottom plan View corresponding to Fig. 17;

Fig. 20 is a `sectional detail taken substantially `at the line 20--20 in Fig..17; and

Fig. 2l is asectional detail taken substantially at the line `21---21 in Fig. 17.

The mechanical pencil shown in the drawings comprises a barrel 10, preferably formed of plasticmaterial, that is fitted with a fixed metal writing tipportion 11 and assembledrearwardlywith a rotatable metal operating cap or sleeve 12 having a metal collar member .13 fitted uforwardly thereon for telescoping rotatably over a short .rear barrel portion of reduced diameter. The remaining rearwardportion of the operating sleeve1-2has aplasticcover member 14 disposed thereover.

The barrel 10 is formed from its rear end with a'relatively short, large diameter, entrance bore 15, a .main bore 16 of slightly reduced diameter that extends forwardly for a major portion of the barrel -length to arelatively short inwardly tapering section at 17, which .ter-

.minates at a tapered annular shoulder 18, and beyond which a terminalfbore 19 is provided to have ashank portion 2t) of the writing tip 11 press fitted .therein and thereby attached in fixed relation to the barrel 10.

The writing tip 11-is in turn formed from its rear .end with three stepped lbores 21, 22, and 23. The rstrearwardly opening bore 21 is they one of largest diameterand is proportioned to receive a longitudinally slotted .guide tube 24 which is fixed to the writing tip 11 by .some suitable means, such as dimpling of the writing tip .shank portion 20 as at 2S. The intermediate writing tip bore 22 is proportioned to receive slidably therein the forward end of a writing lead clutchmem'ber y26, while the smallest forward'bore 23 is of lead-size diameter for allowing a lead L to issue freely therethrough for writing. This forward terminal bore 23 also receives the forward end of Va lead propelling member 27 associated with the clutch member 26 within the guide tube 24 and operable 'for expelling a spent lead from the clutch member 26 through the terminal writing tip ofbore 23 as illustrated in Fig. 7 and explained further below.

The longitudinal slotted guide 'tube 24, .that is fixed `to or anchored inthe writing tip 11 at the forward end of the barrel 10 as noted above, extends rearwardly through the lbarrel 10 in axial relation to reach within the previously mentioned operating sleeve 12 in an extent exceeding that of a spiral feed member 28 assembled coaxially thereon for relative rotation about the resulting common axis. This spiral feed member 28 is preferably of the type disclosed in copending application Serial No. 436,801 tiled June l5, 1954, Aand may be formed of plastic material as v disclosed in copending application Serial No. 436,927 filed lune l5, 1954.

As disclosed in the above noted copending applications, the spiral feed member 28 is characterized by a tubular plastic bodyhaving an internally threaded central bore 29 with opposed longitudinal grooves 30 formed at the exterior surface thereof in a depth extending inwardly to the major diameter of the internal central bore 'threads 31,' so that the spacing between the threads 31 opens through the exterior surface of the spiral feed member 2.3 at the bottom of the longitudinal grooves L30. The spiral feed member 28 is also formed exteriorly with a pair of opposed longitudinal land portions 32, spaced between the opposed grooves 30, at the rear end of which a thrust washer member 33 is seated with angledleg portions 34 thereof recessed in the opposite side Afaces of the land portions 32 andin turn recessed to have a rear end sleeve 35 fixed thereon by dimpling at 36,'and thereby fixed with the thrust washer 33 on the spiral feed member 28. Therear end sleeve `35 is proportioned in di ameter for a slip fit within the operating cap or sleeve 12 so as to provide for rotation of the spiral feed member 28 by turning the operating sleeve 12 withrespect to the barrel 10. At its forward end the spiral feed member 28 is further fitted with a suitable bushing collar 37 or the like formed for bottoming rotatably at the previously mentioned annular tapered shoulder 18 adjacent the forward end of the barrel 10, the upper portion of bushing collar 37, in the arrangement illustrated in Fig. 2, being slotted to engage a rib at the lower end portion of spiral feed member 28 so as to key the feed member 28 and bushing 37 for rotation together.

The spiral feed member 28 is maintained in assembled relation within the barrel for rotation from the operating sleeve 12 by means of a retaining element 38 fixed at the rear end of the longitudinally slotted guide tube 24 to bear forwardly at the rear face of the thrust washer 33; the rear end portion of the guide tube 24 being additionally slotted at 39 opposite the longitudinal slot therein to have the retaining element 38 disposed therethrough, and the guide tube 24 being crimped inwardly above the retaining element 38 to lock it in place. The retaining element 38 is formed as a pin member having a straight length disposed through the slotted rear end of the guide tube 24 and extending suiciently at opposite sides of the guide tube 24 to overlie an adjacent portion of the rear face of thrust washer 33. The retaining element 38 may, if desired, be further formed with arcuate extensions 41 arranged for disposition within a recess formed at the rear face of the thrust washer 33 by a cylindrical boss 42, so as to provide for increased frictional contact between the retaining element 38 and the thrust washer 33 and thereby provide further resistance to inadvertent retracting motion of the feed mechanism under writing pressure.

In addition to the guide tube 24 and spiral feed member 28, the lead feed mechanism further comprises the previ ously mentioned clutch member 26 and propelling mem` ber 27. The propelling member 27 is formed with a rear nut portion 43 and a forward shank portion 44. The nut portion 43 is arranged in the guide tube 24 rearwardly of the clutch member 26 and has a lug portion 45 formed thereon to extend laterally through the longitudinal slot in the guide tube 24 and engage the threads 31 of the spiral feed member 28 for effecting longitudinal or axial sliding movement of the propelling member 27 within the guide tube 24 upon rotation of the feed mernber 28. The shank portion 44 of the propelling member 27 extends forwardly from the nut portion 43 for slidable disposition within the clutch member 26 and has the side thereof opposite the nut portion lug 4S notched so as to form a rearwardlyl facing shoulder 46 forwardly thereon and a rearwardly spaced forwardly facing shoulder 47; being advantageously angled so as to face outward ly as well as forwardly.

The clutch member 26 is in turn formed intermediate its length with ears 48 arranged for bottoming at the rear* wardly facing shoulder 46 on the propelling member shank portion 44 and is further formed with a flexible arm portion 49 extending rearwardly of these ears 48 to the forwardly facing shoulder 47. Adjacent its rear end this exible arm portion 49 has a boss 50 formed outwardly therein for normally riding the inner face of the guide tube 24 so as to maintain the flexible arm por tion 49 disposed inwardly in abutment with the forwardly facing shoulder 47 and thereby tix the clutch member 26 on the propelling member 27 for movement therewith within the guide tube 24, as seen best in Fig. 2. Adjacent its forward end, however, the guide tube 24 has an aperture 51 aligned therein to receive the boss 50 and thereby allow outward shifting of the clutch member flexible arm portion 49 to release the propelling member 4 27 for suliicient separate axial movement adjacent the forward end of guide tube 24 to eject a spent lead from the clutch member 26, as illustrated in Fig. 7.

This separate movement of the propelling member 27 is initiated when rotation of the spiral feed member 28 has resulted in advancing the clutch member 25 in guide tube 24 to the point 'at which the boss 58 on the clutch member flexible arm portieri 49 reaches the guide tube aperture S1v and is thereby released for shifting laterally outward. At the same time, the forward end of clutch member 26 bottoms in the intermediate bore 22 of writing tip 11 with a resulting reaction at the angled forwardly facing shoulder 47 of propelling member shank portion 44 that displaces the flexible arm portion 49 outwardly to release the propelling member 27 for further separate advancement upon continued rotation of the spiral feed member 28 until the propelling member nut portion 43 bottoms at the forward end of the feed member 28 with the shank portion 44 projecting slightly from the lead-size bore 23 at the forward end of writing tip 11.

After ejection of a spent lead from the clutch member 26 by such separate movement of the propelling member 27, reverse rotation of the spiral feed member 28 results in retracting propelling member 27 within guide tube 24 so as to bottom the clutch member ears 48 again at the rearwardly facing shoulder 46 on the propelling member shank portion 44 and thereby force the clutch member boss 50 from the guide tube aperture 51 causing it again to ride the inner face of the guide tube 24 and return the flexible arm portion 49 to abutting position at the forwardly facing shank portion shoulder 47 to restore the fixed disposition of the clutch member 26 on the propelling member 27 for movement therewith withw in the guide tube 24.

In connection with this retracting movement of the propelling member 27 in the guide tube 24 it sllould also be noted that the forward face of the thrust washer 33 is formed with a plurality of spaced radial lugs 5'2 surrounding the guide tube 24 within the central bore 29 of spiral feed member 28. These lugs 52 are arranged so that the front sides thereof facing in the dierction in which the spiral feed member 28 is rotated for retracting the propelling member 27 lie in radial planes with respect to the axis of feed member 28, while the opposite or back sides thereof are slanted at about 45 from thc extending lug edges. By this arrangement, the thrust. washer lugs 52 are disposed for selective lateral abutment with the lugs 45 of the propelling member nut portion 43 so as to lock the spiral feed member 28 against rotation and thereby stop further rearward movement of the propelling member 27 before it can jam or wedge against the forward face of the thrust washer 33 upon reaching its fully retracted position within the guide tube 24 and spiral feed member 28.

As a result, the threads 31 of spiral feed member 28 are afforded positive protection against thrust damage from overtravel of propelling member 27 adjacent the rear end of guide tube 24. Without such protection, the feed member threads 31 may be subjected to severe thrust strain by the wedging action of the propelling member lug portion 45 between the forward face of thrust washer 33 and the rearmost feed member threads 31 if rotation of feed member 28 is continued after propelling member 27 has been fully retracted. The thrust strain resulting in this situation is directed to a principal extent axially of the feed member 28 so as to be exerted across the threads 31 in the direction most likely to damage them.

Thrust strain of this sort is particularly damaging when a plastic spiral feed member 28 of the type disclosed in the previously noted copending applications is employed, because this type of feed member 28 has substantial lengths of its threads 31, at the longitudinal grooves 30, that are unsupported laterally and that are accordingly s relatively weak against such a thrust strain so as to be broken rather easily'if thepropelling'memb'er'27 is made to overtravel carelessly at the rear end of the feed'member 28. By forming the thrust washer 33 with the for ward-face lugs 52, however, any possibility of such overtravel is entirely eliminated.

A spaced plurality of the lugs 52 are provided on the thrust washer 33 so as to allow for varying registration therewith of the spiral feed threads `31, the spiral disposition of which in the body'of the feed member 28 may be yrotated differently in different feed members of the type disclosed in the above noted copending applications. Also, the back sides of the lugs 52 are slanted, as noted above, kso that the propelling member lug portion 45 may slip past a first thrust washer lug 52 at which it does not abut sufficiently for seating adequately against the front face ofl a succeeding lug 52 without any danger of otherwise creating a thrust strain, such as is being provided against, by jamming at the extending edge of the first lug'SZ.

The present invention has been described in detail above `for purposes of illustration only and is not intended to be limited to this description or otherwise except as defined in the appended claims.

I claim:

1. In a mechanical pencil, a guide tube, a clutch member and a propelling member slidably disposed in said guide tube, said propelling member comprising a shank portion extending forwardly for slidable disposition within said clutch member and having a rearwardly facing shoulder formed forwardly thereon and an angled shoulder formed rearwardly thereof facing forwardly and outwardly, said clutch member having ears formed thereon intermediate its length for bottoming at the rearwardly facing shoulder on said propelling member shank portion and having a flexible arm portion extending rearwardly of said ears to said angled shoulder, the inner face of said guide tube maintaining said flexible arm portion inwardly disposed in abutment with said angled shoulder and thereby fixing said clutch member on said propelling member shank portion for movement therewith within said guide tube except adjacent the guide tube forward end at which said guide tube is formed for allowing outward displacement of said flexible arm portion by said angled shoulder to release said propelling member for separate movement.

2. In a mechanical pencil, a longitudinally slotted guide tube, a clutch member and a propelling member slidably disposed in said guide tube, said propelling member comprising a rear nut portion having a lug thereon extending laterally through the longitudinal slot in said guide tube and a shank portion extending forwardly for slidable disposition within said clutch member, the side of saidfshank portion opposite said nut portion lug having a rearwardly facing shoulder formed forwardly thereon and an 'angled shoulder formed rearwardly thereof facing forwardly and outwardly, said clutch member having ears formed thereon intermediate its length for bottomingfat the rearwardly facing shoulder on said propelling member shank portion and having a flexible arm portion extending rearwardly of said ears to said angled shoulder, said flexible arm portion being maintained inwardly disposed in abutment with said angled shoulder by the inner face of said guide tube to fix said clutch member on said propelling member shank portion for movement there* with within said guide tube except adjacent the guide tube forward end at which said guide tube is formed for allowing outward displacement of said flexible arm portion by said angled shoulder to release said propelling member for separate movement.

3. In a mechanical pencil, a longitudinally slotted guide tube, a clutch member slidably disposed within said guide tube and having the forward end thereof formed for gripping a lead, and a propelling member slidably disposed in said giude tube and rearwardly of said clutch member, said propelling member comprising a rear nut portion having a lug thereon extending laterally through the longitudinal slot in said guide tube and a shank portion extending forwardly for slidable disposition within said clutch member, the side of said shank portion opposite said nut portion lug having a rearwardly facing shoulder formed forwardly thereon and an angled shoulder formed rearwardly thereof facing forwardly and outwardly, said clutch member having ears formed thereon intermediate its length for bottoming at the rearwardly facing shoulder on said propelling member shank portion and having a flexible arm portion extending rearwardly of said ears to said angled shoulder, said flexible arm portion having a boss formed outwardly therein adjacent its rear end and normally riding the inner face of said guide tube so as to maintain said arm portion disposed inwardly in abutment with said angled shoulder and thereby x said clutch member on said propelling member shank portion for movement therewith within said guide tube, and said guide tube having an aperture adjacent its forward end aligned with the boss in said clutch member flexible arm portion for receiving said boss to allow outward shifting of said flexible arm portion so as to release said propelling member for sufficient separate movement adjacent said guide tube forward end to eject a spent lead from said clutch member.

4. In a mechanical pencil, a feed mechanism comprising a longitudinally slotted guide tube, a clutch member and a propelling member disposed for axial sliding movement in said guide tube, and a spiral feed member coaxially surrounding said guide tube and rotatable with respect to said guide tube about the common axis thereof, said propelling member being formed with a rear nut portion and a forward shank portion, said nut portion being arranged rearwardly of said clutch member and having a lug thereon extending laterally through the longitudinal slot in said guide tube and engaging said spiral feed member for effecting axial sliding movement of said propelling member within said guide tube upon rotation of said feed member, said shank portion extending forwardly for slidable disposition within said clutch member and having the side thereof opposite said nut portion lug notched to present spaced forwardly and rearwardly facing shoulders thereat, said clutch member having ears formed thereon for seating in said notch and bottoming at said rearwardly f facing shoulder and having a flexible arm portion extending rearwardly of said ears to said forwardly facing shoulder, the inner face of said guide tube maintaining said flexible arm portion inwardly disposed in abutment with said forwardly facing shoulder and thereby fixing said clutch member on said propelling member shank portion for axial movement therewith within said guide tube except adjacent the guide tube forward end at which said guide tube is formed for allowing outward flexing of said clutch member flexible arm portion to release said propelling member for separate movement.

5. In a mechanical pencil, a barrel, a longitudinally slotted guide tube fixed within said barrel adjacent its forward end, a spiral feed member surrounding said guide tube within said barrel and rotatably bottomed forwardly therein, a thrust washer fixed on the rear end of said feed member, means engaged by said guide tube adjacent its rear end and held thereby in forwardly bearing relation at the rear face of said thrust washer, a clutch member and a propelling member disposed for longitudinal sliding movement in said guide tube, said propelling member comprising a nut portion and a shank portion, said nut portion being arranged rearwardly of said clutch member and having a lug thereon extending laterally through the longitudinal slot in said guide tube and engaging said spiral feed member for effecting longitudinal sliding movement of said propelling member within said guide tube upon rotation of said feed member, said shank por- 7 tion extending forwardly for slidable disposition within said clutch member with the side thereof opposite said nut portion lug having a rearwardly facing shoulder formed forwardly thereon and an angled shoulder formed rearwardly thereof facing forwardly and outwardly, said clutch member having ears formed thereon intermediate its length for bottoming at the rearwardly facing shoulder on said propelling member shank portion and having a flexible arm portion extending rearwardly of said ears to said angled shoulder, said flexible arm portion being maintained inwardly disposed in abutment with said angled shoulder by the inner face of said guide tube to tix said clutch member on said propelling member shank portion for movement therewith within said guide tube except adjacent the guide tube forward end at which said guide tube is formed for allowing outward displacement of said exible arm portion by said angled shoulder to release said propelling member for separate movement adjacent said guide tube forward end, and said thrust washer having a plurality of radial lugs formed at the forward face thereof about said guide tube for selective lateral abutment with said propelling member nut portion lug adjacent the rear end of said guide tube to stop movement of said propelling member` thereat.

6. in a mechanical pencil, a barrel, a longitudinally slotted guide tube fixed within said barrel adjacent its forward end and extending rearwardly and axially therein, a spiral feed member coaxially surrounding said guide tube within said barrel and rotatably bottomed forwardly therein, a thrust washer fixed on the rear end of said feed member, means engaged by said guide tube adjacent its rear end and held thereby in forwardly bearing relation at the rear face of said thrust washer, a clutch mem her slidably disposed within said guide tube and having the forward end thereof formed for gripping a lead, and a propelling member slidably disposed in said guide tube rearwardly of said clutch member and comprising a nut portion having a lug thereon extending laterally through the longitudinal slot in said guide tube and engaging said spiral feed member for effecting longitudinal sliding movement of said propelling member within said guide tube upon rotation of said feed member, said clutch member being confined by said guide tube for engaging said propelling member and moving therewith except adjacent the guide tube forward end at which said guide tube is formed to release the engagement of said clutch member with said propelling member and allow sufficient separate forward movement of said propelling member to eject a spent lead from said clutch member, said clutch member being bottomed adjacent the forward end of said barrel upon such release and being thereby held stationary during the separate forward movement of said propelling member, said propelling member nut portion bottoming at the forward end of said spiral feed member to terminate said separate forward movement, and said thrust washer having a plurality of radial lugs formed at the forward face thereof about said guide tube for selective lateral abutment with said propelling member nut portion lug at the rear end of said spiral feed member to stop rearward movement of said propelling member thereat.

7. In a mechanical pencil, a barrel, a longitudinally slotted guide tube fixed within said barrel adjacent its forward end and extending rearwardly and axially therein, a spiral feed member coaxially surrounding said guide tube within said barrel and rotatably bottomed forwardly therein, a thrust washer fixed on the rear end of said feed member, means engaged by said guide tube adjacent its rear end and held thereby in forwardly bearing relation at the rear face of said thrust washer, and a propelling member slidably disposed in said guide tube and comprising a nut portion having a lug thereon extending laterally through the longitudinal slot in said guide tube and engaging said spiral feed member for effecting longitudinal sliding movement of said propelling member within said guide tube upon rotation of said feed memberber, and said thrust washer having a plurality of radial lugs formed at the forward face thereof and spaced about said guide tube for selective lateral abutment with said propelling member nut portion lug adjacent the rear end of said guide tube to stop movement of said propelling member thereat.

8. In a mechanical pencil, the structure dened in claim 7 and further characterized in that the radial lugs at the forward face of said thrust washer have the sides thereof that face in the direction in which said feed member is rotated for retraction of said propelling member formed in radial planes with respect to the axis of said feed member and the opposite sides thereof slanted from the extending edges of said first mentioned sides.

9. ln a mechanical pencil, the structure defined in claim 7 and further characterized in that said guide tube is additionally slotted adjacent the rear end thereof opposite the longitudinal slot therein, the means engaged by said guide tube and held thereby in forwardly bearing relation at tbe rear face of said thrust washer comprises a pin member having a straight length disposed through the slotted rear end of said guide tube and extending at opposite sides thereof to overlie an adjacent portion of the rear face of said thrust washer, and said guide tube being inwardly crimped rearwardly of said pin member to lock it in place at the rear face of said thrust washer.

l0. In a mechanical pencil, the structure defined in claim 9 and further characterized in that the straight length of said pin member has arcuate extensions formed at the ends thereof, and the rear face of said thrust washer is formed with a cylindrical recess in which said arcuate extensions are frictionally seated.

References Cited in the file of this patent UNITED STATES PATENTS 1,793,237 Meilner Feb. 17, 1931 1,826,266 Wehn Oct. 6, 1931 2,511,301 Smith June 13, 1950 2,633,827 Harris et al. Apr. 7, 1953 2,700,960 Liguori et al. Feb. 1, 1955 2,767,687 Vierling Oct. 23, 1956

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