US2063637A - Mechanical pencil - Google Patents

Description

Dec. s, 1936.

M. sTssELl MECHANICAL PENC IL Filed Jan. 22, 193

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l .Patented Dec. 1936 y UNITED STATES PATENT OFFICE uEcnaNloaL renom mx situa'. zum. summa applicati@ January zz, 193e, sean No. 60,290

rn swimna -Febrnary13 1935 2 Claims. (Cl. 1Z0-18) are required for pushing the lead forward and backward.

This disadvantage is overcome by the presentinvention by the provision of two threaded mem- .bersV which propel the lead with the aid of the '15 propelling rod when turning' one of them and by blocking the advance of the one of said members which is moved axially against any undesired shiftgbymeans of a laterally springy brake-stop. In the accompanying drawing the object of the invention is illustrated in an example of design as a mechanical pencil for thin and ilat leads.

' Fig. 1 isa longitudinal section of tbe pencil;

Fig.- 2, a longitudinal section of the pencil turned 90 about its axis;

Fig. 3, a lateral view of anexample of the propelling rod;

Fig. 4, a cross-section along line a-b of Fig. 1';

Fig.'5, a cross-section along line cd of Fig. l;

" Fig. 6, a cross-section along line e-f of- Fig. l;

Fig. 7, a cross-section along line g--h of Fig. 1; Fig. 8, a cross-section along line f-k of Fig. 1; Fig. 9, a cross-section along line L-m of Fig. 1; Fig. 10, a section to a larger scale of the writl ing end of the pencil;

Fig. 11, asketch for illustrating the adaptability of the latter; and

Figs. 12 and 13, a variation of the design of the propellingrod.

A shell I is drawn tightly onto a tube 2 so that by turning the shell the tube is also turned. Said tube, being provided with internal threads, is used as one of the two threaded members. Said tube contains a frame.3 lying with a smooth surface'against threads l. Said frame carries a head vIl possessing a stop-ring I6 which latter rests against an end of tube 2 vents any axial shifting of frame 3 tube 2'. A boss 6 of the oriiice head 5 is securely relative to 50 fastened to the frame 3. Said frame 3 contains in its upper part two opposed slits I9 (Fig. 4), and between the latter is bent outwardly, and is somewhat elastically yielding in order to attain a brake-action between frame 3 and tube 2. In

the finished pencil said frame is cylindrical over and thus preits entire length, but possessesla spring-tension at right angles to its axis whichV acts in an outward direction. A threaded drive block I8 lies axially displaceable inside said frame 3 and projects laterally through the slits I9 and thusv en- 5 gages the threads 4 (Fig. 1). A short cylindrical knob I1, provided with spherical segments at both ends, is disposed inside said block I8, and is axially revolvable. Said knob thus may turn in recess I5 without being setobliquely to 10 the axis of the pencil. Said knob furthermore,

' on the outside of said block I8, is rigidly connected to a head I3 (Fig. 3) vwhich carries a narrow propelling rod I2 which latter, in the embodiment shown, possesses'two laterally yield- 15 ing legs I2'a and I2b. Said rod I2 loosely and movably engag a leader-shell whereby said legs act as brakes against the latters inside wall. Said leader-shell carries a head 9 which may displace itself freely through a limited distance 20 in a Arecess 1 of frame 3, said displacement being resisted by the braking action of rod I2. Said leader-Shelli has a round cross-section around its circumference inside said orifice head 5,v and on the inside the cross-section of a thin, rectan- 25 gular and flat lead. Said leader-shell, at its lower end, is flattened down at both sides of part 8a, thus possessing an essentially rectangular cross# sectionv on the outside.' Said end of said shell 8 is cut of! at an oblique angle (Fig. 10) and is 3o provided with rounded edges 8b. The lower writing surface of lead I0, when writing. lies in the same plane as the lower frame-surface of part la (Fie. 1o).

The threads with which the two threaded parts 35 2 and I8 engage may have a high pitch, since the brake-action between frame 3 and'tube 2 prevents a turning of both .said members relative' to each other when lead i0 and partva are pushed down hard onto the writing-surface. Due to said 40 high pitch, propelling `of lead III is effected with a lesser number of turns than would be required in the case of threaded members with less pitch.

If lead. III, before being put to use, is not in the position according to Fig. 10, but drawn back, it 45 maybe brought into said position when screwing .part 8a of the leader-shell 8 down onto the writcally will tux-n with the arrow into position 0c parallel with the edge of the ruler.

The propelling rod l2 could also be spliced from head i3 downwardly in order to serve as a springy brake.

Two independent and individual springs, both bent toward the outside, also could be used as a propelling rod. Moreover, according to Figs. 12 and 13, a narrow spring could at one part of its length possess a longitudinal slit |2c and the two members I2d thus formed and lying adjacent to said slit could be bent sideways and toward the outside.

I claim:

1. In a mechanical pencil, an orlilce head having a longitudinal cylindrical bore, a frame secured to said orifice head and having a chamber,

said frame comprising a pair of outwardly bowed resilient rods forming a pair of laterally opening, longitudinally extending slots therebetween, an internally screw-threaded sleeve around said frame against which said bowed rods frictionally press, means on said frame for securing said sleeve against longitudinal displacement, a leader shell having an externally cylindrical portion within the bore of the orice head, a head on the leader shell located in the chamber of the frame, saidcylindrical portion and leader shell head being longitudinally slidable and rotatable in said bore and chamber respectively, said shell having a longitudinally extending opening of rectangular cross-section; a drive block mounted in said frame between the rods thereof and having screw threaded portions extending outwardly from the frame through the slots thereof and engaging with the threads oi the surrounding sleeve, said block 'having a downwardly opening elongated Vsocket formed therein, a propeller rod of rectangular cross-section extending into the rectangular opening ofthe leader shell, said rod having an elongated knob at its upper end disposed in the socket of the drive block for rotation about a longitudinal axis but held against lateral movement.

2. In a mechanical pencil, an orifice head having a longitudinal cylindrical bore, a frame secured to said oriilce head and having a. chamber, said frame comprising a pair of outwardly bowed resilientrods forming a pair of laterally opening, longitudinally extending slots therebetween, an internally screw-threaded sleeve around said iframe against which said bowed rods frictionally press, means on said frame for securing said sleeve against longitudinal displacement, a leader shell having an externally cylindrical portion within the bore oi' the orifice head, a head on the leader shell located in the chamber of the frame, said cylindrical portion and leader shell head being longitudinally slidable and rotatable in said bore and chamber respectively, said shell having a longitudinally extending opening of rectangular cross-section, a drive block mounted in said Vframe between the rods thereof and having screw threaded portions extending outwardly from the frame throughthe slots thereof and engaging with the threads of the surrounding sleeve, said block having a downwardly opening elongated socket formed therein, a propeller rod of rectangular cross-section extending into the rectangular opening of the leader shell, said rod having an elongated knob at its vupper end dis posed in the socket of the drive block i'or rotation about a longitudinal axis but held against lateral movement, said propeller rod having laterally extending resilient means frictionally engaging the inner walls of the rectangular opening of. the leader shell.

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