US2613643A - Mechanical pencil - Google Patents

Description

Oct. 14, 1952 c, MERRYMAN 2,613,643

MECHANICAL PENCIL Filed Feb. 25, 1950 INVENTOR.

Cari Many/72am Patented ct. 14, 1.952

UNITED STATES PATENT OFFICE MECHANICAL PENCIL Carl Merryman, Melrose Park, Ill., assignor to Dur-O-Lite Pencil Company, Melrose Park, Ill., a corporation of Delaware Application February 23, 1950, Serial No. 145,809 s claims. (c1. 12o-1s) 1 This invention relates to a new and improved mechanical pencil and more particularly to such a pencil having a novel drive tube construction.

Certain types of mechanical pencils have been designed having a barrel section and a tip sectionv which are rotatable relative to each other. The tip section is ,also removable from the barrel section by a linear movement therefrom. In such pencils, the tip section carries a guide tube for thenlead together with a lead advancing plunger threaded into the guide'tube. The plunger fits up into an actuating tube in the barrel section and has va deformed section held against :rotation by the guide tube but linearly movable therein. Thus, relative rotation between the barrel and tip sections serves to move the plunger linearly in the lead guide tube due to its threaded connection to that tube. It has been customary to provide the actuating tube with a lower resilient section gripping the outer face of the upper portion of the lead guide tube to hold the barrel and tip portions together while permitting relative rotation therebetween. The guide tubes have been formed from tube stock formed of spring brass, which material is expensive and somewhat dinicult to work in-deforming the major portion of the tube so that it will hold the plunger against rotation. y

It is an object of the present invention to provide a new and improved mechanical pencil.

It is a further object to provide a new and improved plunger actuating tube construction for such pencils. Y

It is another object to provide a pencil having improved and simplified means for frictionally securing together the barrel and tip sections of the pencil.

It is also an object to provide a construction which is simple to make and relatively inexpensive and, therefore, adapted for commercial production and use.

Other and further objects will appear as the description proceeds. f

I have shown certain preferred embodiments of my invention in the accompanying drawings, in which- Figure 1 is an elevation of the pencil;

Figure 2 is a view similar to Figure 1 but with parts broken away to show theinternal construction; Figure 3 is a plan view of the blank used for forming the actuating tube;

Figure 4 is a face View of the actuating tube;

Figure 5 is a section taken on line 5-5 of Figure 2;

Figure 6 is a section taken on line B-S of Figure 2; and

Figure 7 is a longitudinal section, on an enlarged scale, showing the nose member and the associated portion of the actuating tube.

The pencil, as shown in Figure l, comprises the barrel I I which may be formed of plastic or similar material and the tip section I3. This tip section I3 may also be formed of plastic, with the exception of the metal tip I4 which may be of usual construction, being split at I5 to resiliently grip the lead. The barrel may have a removable cap Iii which may cover an eraser, but such portions of the construction form no part of the present invention.

As shown in Figure 2, the barrel Il is hollow and has the metallic nose member IB permanently secured at its lower end. This nose section I8 has circumferential knurling I9 and a groove 2U which assist in holding it in place in the plastic barrel II i'ixedly for movement as a unit with the barrel. This section I8 is also provided with a circumferential flange 22 which serves to space the barrel section I I from the tip section I3. The nose member I8 is provided with a circumferential bore 24 of uniform circular cross-section.

The actuating tube 26 is formed from a flat blank 2l shown in plan View in Figure 3. This blank has a reduced intermediate section 29 separated from a further reduced end section 3l by notches 32. The upper end of the body of blank 21 is formed with projections Si. When rolledv into tubular form, as shown in Figure 4, the reduced section 29 is tubular and the reduced end section SI is also substantially tubular in shape, although of slightly smaller diameter. The body of the blank 2l is deformed from the circular shape so as to have an intermediate cross-section generally similar to a four-pointed star. AS shown in Figure 6, the lugs 34 are turned down to close the upper end of the actuating tube.

As shown in Figure '7, the tubular portion 29 of the actuating tube has a tight push fit in the bore 24 in the nose member It. The reduced end section 3| is slightly smaller than the bore 24 so that it may be expanded against the resilience of the spring metal of which it is formed.

The lead advancing plunger 36 has a threaded portion 3l' which fits intoa reduced end 39 of the lead guide tube il. This reduced end is threaded so that the guide plunger, upon rotation, will be moved longitudinally of the guide tube. The upper end of the plunger 36 is provided with a deformed attened section 42 which fits into the upper non-circular star-shaped section 21 of the actuating tube in such manner that the plunger 36 cannot rotate relative to the tube but may slide longitudinally therein.

The lead guide tube d is secured into the tip section I3 in such manner that it rotates with the tube, for example in the manner in which similar parts are connected in the patent to Lynn, 2,134,568, of October 25, 1938. Consequently, upon rotating the tip |11 relative to the barrel the tube 49 is rotated and the reduced threaded section 39 acting upon the threaded section 31 of plunger 36 causes linear movement of that plunger. The guide tube 46 is formed of such size as to make a spring fit into the section 3| of the actuating tube 2S. As previously stated, this tube 26 is made of resilient material, preferably spring sel, and a clearance is provided in the nose i8 to permit this connection. The intert, therefore, between the tube 49 and spring tube 3| serves to hold the tip in place upon the barrel while it permits relative rotation between the parts. This actuating tube 2S may be formed in the manner shown of relatively inexpensive spring steel purchased in fiat form by the manufacturer. This is Very much less expensive than the tubular spring brass members which are in general use for the same purpose. The particular arrangement of the reduced split end of section 3| permits the parts to be assembled with a bore of uniform diameter through the nose member |8 and yet allow adequate clearance for the spring action necessary to grip the lead guide tube 40.

An important feature of the construction consists in the fact that the split end section 3| is housed for the major portion of its length in the bore 24 in the nose member. The clearance in the bore 24 is adequate to permit portion 3| to expand suliciently for it to grip the guide tube 40. The clearance is small enough, however, to prevent such excessive expansion of portion 3| as to give it a permanent set so that it would not efficiently grip the guide tube I0. It has been found that a guide tube without this guarding by the nose member is often distorted in use so as to be nefiective in frictionally holding the tip section and barrel section in assembled relation.

While I have shown certain preferred embodiments of my invention, these are to be understood to be illustrative only as it is capable of modification to meet varying conditions and requirements, and I contemplate such variations as come within the spirit and scope of the appended claims.

I claim:

1. In a mechanical pencil comprising a barrel section, a tip section, a lead guide tube secured in the tip section, a lead advancing plunger threaded into the lead guide tube and extending into the barrel section, a nose member fitted into the lower portion of the barrel section, said nose member having a central cylindrical bore extending therethrough, an actuating tube having an intermediate portion of circular cross-section tted tightly into the cylindrical bore and extending for a portion of the length of said bore, the actuating tube having a non-circular upper portion, the lead advancing plunger having a deformed portion tting slidably in the non-circular upper portion of the actuating tube and held against rotation thereby, the actuating tube having a longitudinally split lower portion of circular cross-section extending in the lower portion of the bore in the nose member and having a clearance therefrom, said lower portion terminating adjacent the lower end of the nose member and resiliently gripping the upper portion of the lead guide tube which is tted therein.

2. In a mechanical pencil comprising a barrel section, a tip section, a lead guide tube secured to the tip section and having a cylindrical portion extending up into the barrel section, a nose member xedly secured in the lower part of the barrel section, said nose member having an axial cylindrical bore extending therethrough, a longitudinally split actuating tube in the barrel section, said actuating tube having an intermediate portion tightly fitting in the upper portion of the nose member bore and a lower substantially cylindrical and longitudinally split resilient portion the major part of which lies within the lower portion of the nose member bore, said lower split portion of the actuating tube being smaller than the bore whereby it may be expanded within and clear of the bore to grip resiliently the cylindrical portion of the lead guide tube, the bore limiting expansion of the split portion to an expansion within its elastic limit.

3. In a mechanical pencil comprising a barrel section, a tip section, a lead guide tube secured in the tip section, a lead advancing plunger threaded into the guide tube and extending into the barrel section, a nose member xedly secured in the lower portion of the barrel section, said nose member having a central cylindrical bore extending therethrough, a longitudinally split actuating tube in the barrel section, said tube having an intermediate portion of circular cross section tting tightly in the upper portion of the nose member, said tube further -having a lower portion of approximately circular cross section with a longitudinal split therein the major part of said lower portion being within the bore in the nose member, terminating adjacent the lower face of the nose member and being so related in size to the bore and the lead guide tube as to expand within the bore free of engagement with the bore to resiliently grip the guide tube, the bore preventing any substantial additional expansion such as to expand the tube beyond its elastic limit, the actuating tube having an upper portion coacting with the lead advancing plunger in advancing lead in the lead guide tube.

CARL MERRYMAN.

REFERENCES lCITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,946,085 Lungren Feb. 6, 1934 2,134,568 Lynn Oct. 25, 1938 FOREIGN PATENTS Number Country Date 986 Great Britain 1877 894,857 France Mar. 20, 1944

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