US2245805A - Mechanical pencil - Google Patents

Description

June 17, 1941. L. J. MOST MECHANICAL PENCIL Filed March 30, 1940 INVENTOR BY v LA O EY Patented June 17, 1941 UNITED STATE-S PATENT OFFICE 2,245,805 MECHANICAL PENCIL Lucifer J. Most, Hudsoncounty, N. J. ApplicationMarch30, 1940, Serial No. 326,859 kwarms. (C1. 12o-fis) My invention relates to mechanical pencils and has reference particularly to themeans for actuating the lead. 'The leads used in this' type of mechanical pencil have a very' limitedcros's-sectional area'and'their total massor weight is rather slight. It,`therefore,'becomes necessary to provide means forinsuring the engagement of the lead with the' means' for actuating it at the time'the engagement lis'to take plac between them, for gravity'alone is not sufficient' to' insure such engagement. Other objects of the invention will be pointed out hereinafter,v or will be apparent to one skilled in the art from the disclosure therein.

In the appended drawing'iorming part of this application, Figure '1 vis anenlarged vertical 'section online I-I, Figure'2 through the lower end of a mechanical pencil embodying my inven-r tion; no leads are shownto better illustrate the invention.

Figure 2 is an enlarged crossesection on line 2 2, Figure`1.

Figure '3 is a similar section `on line 3-3, Figure 1. v 1

Figure 4 is an enlarged section on line 4-4, Figure 2 yof the tip end.

Figure 5 is an enlarged top end view of the interiorly threaded member showingits engagement with a lead.

Figure 6 is an enlarged section on linev 6ft-6, Figure 5, and

Figure '7 is a view similar to that of Figure 5, showing the interiorly threaded member provided for a lead of different crossfsection .than that shown in the .other figures.Y

Referringto the 'iigures,` I0 isa .barrel which terminates with a tip II coupled withv the barrel to participate in all the movements thereof. The tip I I is provided at its eXtremitywith a bore I2 .of a circular cross-section to frictionallyengage a lead fed therethrough. As shown the tip end of the bore is splitteobtain the'frictional Contact but any Vother suitable means for that purpose maybe used. The bore I2 enters into an enlarged circular bore I3 in which is mounted revolubly a tube I4. The upper'portion of said tube is revolubly mounted in a bushing I5 keyed to the barrel, as indicated at I6. The upper end of the tube I4 enters an enlarged recess I'I inthe bushing and thereat carries an exterior gear I8 constrained to revolve With the tube. lower end the tube I4 carries within an interiorly threaded member I9, also constrained to revolve with the tube.

A pinion -20 revolubly mounted inthe bushing I5 is in mesh with the exterior gear I8 and an interior gear 2I formed in a ring 22. The ring 22 is coupled to a magazine tube 23 to revolve therewith.

Mounted within the tube I4 is a tube 24 which At thel perfnits the tube I4l to revolve freely about it. The upper end of the tube 24 projects out ofthe tube I4 and thereat carries a washer 25 rmly secured to the exterior'end of the tube 24, and also' firmly secured in the enlarged recess I'I of the bushing I5. The washer 25 also serves as means for preventing longitudinal displacement of the pinion 20 in the bushing. The lower end 26 of the tube 24 isswedged to form a lead guide 'of' the' desiredcross-sectional shape thatv Will by its contour prevent a lead of cooperative crossvsectional contour from turning therein While permitting the lead to move longitudinally. In this particular case, the contour of the lead guide 26 is'triangular and "itis inalignment with the threaded member and thebore I2, which bore also forms a frictional lead guide below the threaded member. The diameter of the bore I2 is Slightly less'than the diameter of the circle inscribng the edgesof'the lead.

.Positioned Within the magazine tube 23 is a washer121, which forms the bottom of said tube and with which it forms' the magazine for leads. The washer is shapedto facilitate the movement of the leads fro-m the magazine into the tube 24 'from where it enters the swedged end 26 of sai'dtube, which swedged end constitutes the lead guide leading to thethreaded member I. This Washer 21 maybe coupled to the magazine tube 23, Aor if desired, free thereof and coupled to the washer 25. In either arrangement it will perform the function described.

As'willbe' seen from Figures 1 and 4, the interiorly threaded member with its tube I4 by which it is driven fare so proportioned thatwhen the pencilis assembled, the lower end of the threadedmember bears on the bottom of the bore'v I3 in they tip. The longitudinal'movement of Ythe threaded member and the tube is prevented by the washerv 25' in the recess I'I and the contact -of the lower end of the swedged end 26 with the upper face of the threaded member I9. 'To insure a positive engagement of a'lead 28 with theinteri'orly threaded member I9, I provide notches 29l in theupper end of the threaded memben'th-atis, .the face adjacent tothe lead gui'de2i whichl guides a lead from the magazine or tube 24.to the threaded member I9. /These notches '29 are cut radiallyinthe wall of the threadedmember I9 and the number of those notches corresponds to the number of Iangles lthe leadihas. In this particular case, the lead is shown triangular, and'therefore three notches haveV been cut. The width ofthe notches a-re such that they would easily accommodate that portion ofthe' lateral surface .of the lead which isto be engaged bythe threads of the member I9.

the magazine l 2 3 revolved relatively to the barrel I0, the ring-221s revolved therewith, causing the interior gear I9 to turn the pinion 2B, Which in turn revolves the gear I8 and therewith the tube I4, which carries the interiorly threaded member I9. The bore I2 which forms the frictional lead guide in the tip and the swedged end 26 which also forms a lead guide above the threaded member, are stationary, being coupled to the barrel as previously described. In consequence of the rotation of the from turning in the guide but permitting the lead y to move longitudinally, a second lead guide of threaded member I9 relatively to the lead guides I2 and 26, the notches 29Y of the threaded member will intermittently register with the adjacent angular portions or the lead guide above the threaded member, thereby permitting the angular portion 3| oi a lead ready to engage the threaded member I9 to enter into the notches 29, through an axial depth of the said notches 2Q. This axial depth must be at least that of a complete convolution of a thread. In consequence of this engagement of the lead portions 3l with the cut away portions in the thread 30 a positive engagement takes place and the further rotation of the threaded member I9 causes the threads to cut into the portion of the lead which lies in the notches Within the threaded part 30.

I By this means I provide a positive engagement between the threaded member and the lead coming thereinto and insure the progress of said lead from the lead guide 26 through the threaded and thereafter through the lead reason for cutting those notches across the face of the threaded member is the fact that the Wall thickness of the interiorly threaded member is very small and to make those notches only within the depth of the thread 30 of the threaded member is impractical.

The frictional lead guide formed by the bore I2 in the tip comes into play only when a lead fed by the threaded member leaves the lead guide 26. It is then that its frictional engagement with the lateral edges of the lead therein prevent its turning when the threaded member is turned, thereby enabling the feeding out of a lead portion from the threaded member. The piece of the lead that may be still engaged in the frictional lead guide I2 is `forced out by a lead following it through the threaded member. 'Ihe threaded portion of the lateral surface of the lead provides a better frictional engagement between the lead and the yielding bore forming the frictional lead guide I2 in the tip than a smooth lead surface.

In Figure 7, the threaded member I9 is shown with notches 29 to accommodate a lead of oval cross-section. It is evident that the lead guides will also be of oval cross-section, and the registration oi said notches 29 with the longer axis of the oval will permit the lead to enter into the threaded member and provide means for a positive engagement between the lead and the threaded member.

It is self-evident that if the cross-section of the lead pencil is polygonal as distinguished from the triangular, the number of notches will correspond thereto. Furthermore, for an oval lead pencil, as shown in Figure 7, four notches may be provided, and for a triangular lead as shown in Figure 5, six notches may be provided, in which case the registration between the cooperating parts of the guide and threaded member will take place at shorter intervals.

circular cross-section for frictionally engaging a Vlead coming from the threaded member to prevent its turning in the second guide, and means for turning the threaded member relatively to the guides.

2. In a mechanical pencil, an interiorly threaded member for engaging a lead directly, a lead guide for directing a lead to the member and having means inherent to its shape for preventing a lead shaped to cooperate with the guide from turning in the guide but permitting the lead to move longitudinally, a second lead guide of circular cross-section for frictionally engaging a lead coming from the threaded member to prevent the lead from turning in the second guide, and means for turning the threaded member relatively to the guides, said threaded member having means in the end adjacent to the rst guide for positively engaging the entering end of lead before said end of lead is engaged by the threads of the member.

3. In a mechanical pencil, an interiorly threaded member for engaging directly a predetermined portion of the lateral surface of a lead, a lead guide for` directing a lead to the member and having means inherent to its shape for preventing a lead shaped to cooperate with the guide from turning in the guide but permitting the lead to move longitudinally, a second lead guide of circular cross-section for frictionally engaging the lead coming from the threaded member, said frictional engagement of the second guide with the lead prevents the lead from turning in the second guide, and means for turning the threaded member relatively to the guides, said threaded member having means for engaging the end por- 45 i tip provided with a lead outlet of circular cross- 5o section shape to frictionally engage a lead therein to prevent the lead from turningV in the outlet, a threaded member in the tip adjacent to the lead outlet, a tubular member housing the thread-ed member and coupled with it and rising above the same Within the tip, a second tubular member within the rst and revoluble relatively thereto, said second tubular member having a reduced portion in proximity of the threaded member shaped to form a lead Vguide having means inherent to its shape for preventing a lead shaped to cooperate withthe guide from turning in said .guide while permitting the lead to move longitudinally, a lead vmagazine in the barrel having means for directing leads into the second tubular membennand motion transmission means fromr the magazine to the first tubular member, said threaded member having means in proximity of the reduced portion of the second tubular member to permit a lead to enter thereinto before the threads of said threaded member engage the lead therein. Y Y

LUCIFER J. MOST.

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