US2172349A - Mechanical pencil - Google Patents

Description

Sept. 12, 1939. P. s. HAu'roN nEcHAnIcAL PENCIL Filed July 12, l1935 INVENTOR Patented Sept. 12, 1939 UNITED STATES PATENT OFFICE This invention relates to mechanical pencils having relatively rotatable manually operable ex' terior parts, the relative rotation of the parts operating housed lead feed mechanism for projecting the lead from the pencil as desired.

It is especially desirable in a mechanical pencil that back feed of the lead during the writing operation be eliminated, and one of the objects of the present invention, among others, is to aiord a more generally simplified structure which will prevent such action.

In my co-pending application Serial No. 66,1, led January 7th, 1935; I have disclosed a pencil embodying a closed internally threaded tubular member and including mechanism to prevent back feed. The present invention employs an open coiled flat strip of metal with the turns spaced to aiford threads and aims to utilize the inherent characteristics of such open coiled strip to prevent back feed and at the same time eliminate the conventional idling space at the end of the threaded member, and yet permit the ejector mechanism to function.

In the types of pencils which include an ejector mechanism the wing or lug of the lead moving element is customarily permitted to idle in a space at the end of the threaded tube or helix. In the present invention, instead of a generally annular space being provided at the end of the threaded feed tube or helix, the lead guide tip is so arranged as to permit the helix to butt against the rear end of the writing tip, thereby permitting the helix to operate in a partially compressed state. The opposite end of the helix bears against a washer fastened to the slotted tube.

Another object of the invention is to provide a simple and positive construction for locking the writing point to the slotted feed tube.

A still further object of the invention is to 4@ provide a structure wherein the usual clip acts as a friction brake to prevent back feed of. the lead.

Yet another object of the invention is to provide a simple construction whereby the ejector 4 5 pin is kept in its proper alignment during operation so that especially upon its retraction it doesl not jam in the pencil so that it cannot be pulled back all the Way.

Other characteristics and objects of the inven- 50 tion will be apparent as the description proceeds.

While one embodiment of the invention is illustrated in the accompanying drawing, it is to be understood that this embodiment merely serves as an illustration of the underlying principles of 1:5 the invention so that they may be readily comprehended by those skilled in the art and is not intended as limiting the invention to the speciilc form disclosed therein. Y

In said drawing:

Fig. 1 is a longitudinal sectional view of one 5 modification.

Fig. 2 is a section of Fig. 1 on the line 22.

Fig. 3 is a section of Fig. 1 on the line 3*-3.

Fig. 4 is a perspective View of the writing end of the pencil partly fragmentary and partly in 10 section.

Fig. 5 is a partly fragmentary and partly sectional view of some of the elements at the writing end of the pencil.

Fig. 6 is a modified form of the pencil shown u in Fig. 1.

Fig. 7 is a section of Fig. 6 on the line 1 1.

Fig. 8 is a section of Fig. 6 on the line 8 8. Referring more particularly to the drawing and more especially to Figs. 1 to 5 inclusive, a 20 pencil casing or shell comprises a plurality of relatively rotatable manually operable Yexterior parts A and B, the enlarged end A of part A being extended beyond the end of the pencil and ail'ording a shouldered sleeve or ferrule to receive 25 an eraser seat C in which the end of a conventional eraser C is fixed. The part A has a reduced portion A" opposite to the eraser seat journalled inthe end of the part B and having a running t therewith. 30

The member A is provided with and finished oi by a bead D which also determines the extent to which part A can project into member B. The reduced portion A" of the manually operable part A is journalled in and has a running lit with the 35 inside periphery of the manually operable part B and is further reduced at E to form a sleeve having a driving t with the outside of an axial helix F. This helix may be and preferably is conveniently formed by coiling a iiat strip of metal, which by proper selection of its width and spacing of its turns provides the desired thread pitch for feeding a lug or wing G laterally projecting from a lead grip sleeve H and wing or lug J of an ejector pin J', the latter being-ar- 45 ranged to slide forwardly in the lead grip sleeve when the latter has reached the end of its stroke for the purpose of ejecting short lengths of lead as will be readily understood.

The wings or lugs G and J of the ejector and lead grip sleeve respectively are guided in the longitudinal slot of a slotted tube K concentrically arranged within the helix F, relatively rotatable therewith and forming with the helix the principal parts of the feed mechanism;

In the modication shown in Figs. 6, 'l' and 8, instead o! the manually operable rotatable part A and helix drive being formed in o ne piece, the helix drive U has a friction iit with a separate eraser ferrule V supporting aneraser in a manner similar to member A' of Fig. 1. 'I'he drive member U is reduced at U to form a driving nt with the helix F which is substantially identical with that shown in Fig. l.

When the pencil has a slotted tube K that is not sumcientiy rigid, such as when used with pencils for extra long leads, the braking action of washer R and point shank M against the ends of the spiral F may not be sumcient. In that case I employ a separate braking member W shown in Fig. 6. This is an annular split ring gripping over the driving sleeve U shown in Fig. 6. 'I'he lower part oi the braking member or sleeve W may be shaped to have non-rotatable contact with the casing B. The split polygonal member X may be placed with its angles in the angular corners of the casing B and have its sides bearing on the helix for additional brafing action if desired.

I claim: l

1. A mechanical pencil comprising a lead guide tip `having a tapered portion at one end and a reduced portion at the other end, said tip having a lead guide bore in its tapered portion and a connecting bore of larger diameter in the reduced portion, a slotted tube having Aan inside diameter substantially the same as that of the lead guide bore and fitting at one end into the bore of larger diameter, said tube having an opening in its bore engaging end, said reduced portion having a depressed portion engaged in the slot ot the tube to act as a key to prevent rotation of tip and slotted tube, and a. somewhat similar depressed portion engaged in the said opening to prevent longitudinal movement between said tube and tip. v

2. A mechanical pencil comprising a lead guide tip having a tapered .portion at one end and a reduced portion at the other end, said tip having a lead guide bore in its tapered portion and a connecting bore of larger diameter in the reduced portion, a slotted tube having an inside diameter substantially the same as that ot the lead guide bore and iitting at one end into the bore of larger diameter, said reduced portion having an integral oil-set portion engaged in the' slot of the tube to act as a key, said tube having an opening opposite the slot therein, said reduced portion having a slot cut thereinto and extending from the outer edge ofthe reduced portion to the outer end of the oiI-set portion and acting as a wing-receiving recess, and -a similar oi'l'set portion formed in said reduced portion and engaged in the said opening to prevent longitudinal separation of said tube and "tip, y

PAUL s. HAU'roN.

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