US2611342A - Drive construction for mechanical pencils - Google Patents

Description

Sept. 23, 1952 c. MERRYMAN DRIVE CONSTRUCTION FOR MECHANICAL PENCILS Filed Jan. 30, 1951 IN V EN TOR. Merymaf;

i at ent'eci Sept. 23 195? V DRIVE CONSTRUCTION FOR MECHANICAL PENCILS Carl Merryman, Melrose Park, 111., as'signor to Dur-O-Lite Pencil Company, Melrose Park, 111;, e a corporation of Delaware Application January 30, 1951, Serial No. 208,487

4 Claims. 1

Thisinvention relates to a new and improved mechanical pencil construction and more particularly to a construction which insures posi-, tive feedof the lead when the pencil has been filled with lead and assembled for use.

A well known form of pencil comprises a lead 'guidetube, having aspiral opening in the wall and having a plunger or follower fitting in the tube with a portion projecting through the spiral openingv and fitting in a longitudinal groove in an enclosing barrel. Relative rotationbetween the barrel and guide tube serves to move the follower. downwardly of the tube to feed the lead out thelower end of the tube Manufacturing tolerances are such that if the user merely drops the'follower into the guide tube and does not feed it into the spiral before re-assembling the pencil for positivelyfeeding the follower into the spiral when the parts arelassembled. I V. "Itils a vfurther object .to provide such pencils with internal guide means at the upper end thereof whereby the followeris' guided and forced into thespiral as the parts areassembled. r 7 It is anadditional object to provide such a cons truction which will operate efiiciently with the parts varying in size throughout the range of normal manufacturing tolerances.

-It is also an object" to provide a pencil which is simple in design and adapted for commercial production and use. I

Other and further objects will appear as the description proceeds.

. I haveshown certain preferredembodiments of my invention in the accompanying drawing in which- 7..

Figural isan elevation of a complete pencil; Figure 2 is a longitudinal section of the upper portion of the pencil on an enlarged scale; I

Figure -3 is a cross section takenon line 3-3 of Figure 2;

Figure 4 is a cross ..section taken. on line 4-4 of Figure 2 and Figure 5 is a cross section taken on line 5-5 of Figure 2. I r r 7 In theidrawing the pencil is shown as having a barrel H with an upper reduced portion l2 on which is fitted cap l3. These parts may be made of plastic or other suitable material and the cap is normally secured permanently in place by an adhesive or plastic solvent or other desired means. The tip 14 is provided with slots [5 so that it resiliently grips the lead 16. v The tip I4 is frictionally held in assembled relation to the barrel by conventional means forming no part of the present invention and not shown.

The spiral guide member 18, shown in Figure 2, is securedto the tip l4 and is rotated by rotation of-the tip to feed the lead downwardly by means of the mechanism shown. This mechanismcomprises a follower 20 having an outwardly fbent portion 2 and a downwardly bent portion- 22, the portion 21 passing between the turns of the spiral guide member It. This portion 2| preferably has its upper and lower surfaces flattened on inclined planes corresponding to the pitch of the spiral opening in member l8.

The hollow barrel 1 Iis providedwith one ormore longitudinally extending internal grooves Z4 adapt ed to receive the downturned portion 22 of the follower 26, The groove 2 3 into which this per:- tio'nof the follower is fitted prevents the follower from rotating relative to the barrel. Thus when the spiral guide it is rotated relativepto the barrel by turningflthetipl i upon the barrel the follower'orplun'ger 2B is fed downwardly, forcing the lead I6 downwardly through i the resilient grip of the split tip 14. 7

The general pencil construction V described above has been used heretofore and in itself forms no part ofthe present invention.

In the useof suchpencils the lead is renewed by pulling the tip Maway from the barrel, the. tip bringingiwith it the spiral guide l8 and the follower 2!]. .The follower 20 is held against rov tation by thefingers and thetip it together with the member 13 are rotated:.to cause member}!!! to rise out of member 18. A new lead is dropped into member 18 and the plunger 20 dropped upon the lead. The member 1 8 is then replaced in the barrel with the portion}? of member refittin irra groove:25l. The barrel H and tip are then given relative rotation to movefollower' 20 down to force the lead downwardly .until a'suitable length projects beyond tip M for use. 73

These pencils are produced in large quantities and it is impractical in production to manufacture the parts with such-closetolerances that the upper end ofspiralmember lBmakesa closev fit with the under face of the cap I3. The inter-' mediate portion2l of the follower 20 may rest on the upper edgepfthe memberfli or may be held above that edge by contact with the lead when the parts are reassembled. There may be sufficient clearance between the top member I8 and the under face of cap I3 so that the portion 2| merely rides around on top of member 18 when the parts are given relative rotation. If it does not enter the spiral in member [8 the lead is not fed down and the pencil is inoperative.

The members l8 are cut from continuous spiral lengths and the upper edge will have a. comparatively sharp point above the spiral opening as indicated at 21 in Figure 5. If there is a clearance between the under face of the cap 13 and the upper edge of member l8, which clearance is of less dimension that the thickness of portion 2| of the follower 20, this portion 2| may become jammed in the point 2'! when the parts are thrust together and given relative rotation.

According to the present invention the inner face of the cap [3 is provided with a cup shaped member 29 having a central downwardly extending lug 3%! adapted to fit within the upper end of member [8. The lateral walls 32 of the cup 29 have their inner edge chamfered to form a sloping or conical surface, as shown at 34, to engage the outer edge of portion 2! of the follower 20.

The combination of lug 30 and chamfered edge 34 engages the upper face and outer edge of portion 2| of follower 20 when the parts are assembled with this portion resting on the upper edge of member l8 and the member I8 is thrust upwardly into the barrel I l. The tip I4 is turned relative to the barrel l l as the parts are inserted and the portion 22 of member 20 is held against rotation by the groove 24. As the upward thrust and turning motion is continued the lug 30 and chamfered edge 34 force the member 20 downwardly into the spiral opening in the member l8 as soon as the portion 2| of member 20 reaches that opening. Thus the member 20 is fed down the spiral and cannot fail to enter the spiral and cannot become jammed at the upper end of the spiral. It will be understood that the construction shown may be varied to meet difiering conditions or requirements. For example the lug and chamfered edge may be formed integrally with the cap ratherthan as an insert in the cap. I therefore contemplate such modifications as come within the spirit and scope of the appended claims.

In the claims:

1. A mechanical pencil comprising a barrel, a lead guide tube having a spiral opening formed in its walls, a tip permanently secured to the lead guide tube and frictionally fitted on the lower end of the barrel, the lead guide tube and tip being jointly removable from the lower end of the barrel, the barrel being tubular and having an inner longitudinal groove, a follower fitted in the guide tube and having a portion extending through the spiral opening and into the barrel groove, the follower being removable from the upper end of the guide tube to permit insertion of lead in said tube, the barrel having a closed upper end, the inner face of the upper end having 9. lug extending downwardly therefrom and into the upper end of the guide tube.

2. A mechanical pencil comprising a barrel, a lead guide tube having a spiral opening formed in'its walls, a tip permanently secured to the lead guide tube and frictionally fitted on the lower end of the barrel, the lead guide tube and tip being jointly removable from the lower end of the barrel, the barrel being tubular and having an inner longitudinal groove, a follower fitted in the guide tube and having a rounded portion extending through the spiral opening and into the barrel groove, the follower being removable from the upper end of the guide tube to permit insertion of lead in said tube, the barrel having a closed upper end, the inner face of the upper end having a lug extending downwardly therefrom and into the upper end of the guide tube, the inner face also having a sloping circumferential portion adapted to engage the portion of the follower extending outwardly of the spiral guide.

3. A mechanical pencil comprising a barrel, :1 lead guide tube having a spiral opening formed in its walls, a tip permanently secured to the lead guide tube and frictionally fitted on the lower end of the barrel, the lead guide tube and tip being jointly removable from the lower end of the barrel, the barrel being tubular and having an inner longitudinal groove, a follower removably fitted into the guide tube, said follower having a portion extending downwardly in the tube, an intermediate portion extending through the spiral opening in the guide tube and an outer downwardly extending portion fitting in the inner groove in the barrel, the intermediate portion of the follower having its upper and lower faces formed to conform to the pitchof the spiral in the guide tube, the follower being removable from the upper end of the guide tube to permit insertion of lead in said tube, the barrel having a closed upper end, the inner face of the upper end having a downwardly extending lug fitting loosely within the guide tube- 4. A mechanical pencil comprising a barrel,,a lead guide tube having a spiral opening formed in its walls, a tip' permanentlysecured to the lead guide tube and frictionally fitted on the lower end of the barrel, the lead guide tube and tip being jointly removable from the lower end of the barrel, the barrel being tubular and having an inner longitudinal groove, a follower remov= ably fitted into the guide tube, said followerhav-" ing a portion extending downwardly in the tube, an intermediate portion extending through the spiral opening in the guide tube and an outer downwardly extending portion fitting in the inner groove in the barrel, the intermediate por-- tion of the follower having its upper andlower faces formed to conform to the pitch of the spiral in the guide tube, the follower being remov ablefrom the upper end of the guide tube to permit insertion of lead in said tube, the barrel having a closed upper end, the inner face of the upper end having a downwardly extending lug of circular cross section fitting loosely within the guide tube, said inner face also having'a conical circumferential portion adapted to engage the upper face of the portion of the follower extendthe Number Name Date 1,647,059 Smith Oct. 25, 1927 2,072,711 Cuthbert et a1. Mar. 2, 1937 2,116,136 Beisang May 3, 1938 2,145,450 Lynn 1 Jan. 31, 1939

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