US2769428A - Pencil sharpeners - Google Patents

Description

Nov. 6, 1956 R. A. ONANIAN 2,769,428

- PENCIL SHARPENERS Filed July 12, 1955 7V ii I II I D iI INVENTOR R/ C HARD A. O/V/l/V/A/V 1 BY Mfiw ATTORNEY Unite s w th The present invention relates to pencil Sharpeners, and more particularly to pencil sharpeners adapted to sharpen replaceable leads held in mechanical, shouldered lead holders of the type used by draftsmen.

The art of pencil sharpeners is of course quite old, and has concerned itself primarily with the type of sharpener which must be operated with both hands. Naturally, such two-handed operation has been highly inconvenient for draftsmen and others who have frequent resort to a pencil sharpener during the course of their work; and hence, it has been proposed to provide rigidly mounted sharpeners into which the pencil or lead holder may be inserted and rotated to sharpen the point. However, such rigidly mounted sharpeners, although adaptable to onehanded operation, nevertheless caused a great deal of jamming and breakage of pencil points and did not impart a desirably tapered point to the pencil. Hence, it was proposed to provide sharpeners which were adapted for one hand operation and in which the sharpening means was mounted for helical movement relative to its support so that the sharpening elements would rotate about the pencil and sharpen the point evenly on all sides when the pencil was inserted in the device.

Nevertheless, such pencil sharpeners of the prior art, even most highly developed as described above, still had a large number of disadvantages which rendered them highly inconvenient for frequent use. To begin with, such sharpeners, which were driven by the pressureof the pencil point, inevitably exerted excessive torsional and fiexural stresses on the point and often caused the point to snap or fracture. Moreover, such prior art sharpeners were subject to jamming or clogging of the broken points in the sharpener between the cutting elements thereof, or, if the point were successfully sharpened without breaking, then the filings removed from the point would jam or clog the device.

And even in the best sharpeners known heretofore, it had been necessary to adjust the length of the lead protruding from the holder so that a sufficient length would be provided to accommodate the desired taper of the point, but without withdrawing such a great length of lead as would be liable to break of]? during sharpening. Moreover, pencil leads sharpened by use of the prior art sharpeners were of necessity very carefully inserted in the sharpener so as to avoid misalignment which would result in a broken point, or at best a flattened and spaded point. Furthermore, the pencil sharpeners previously known all suffered from the great disadvantage that they could not impart to a pencils point a taper suificiently fine for use in drafting work which would not at the same time be undesirably weak. Such long, tapered points were not only liable to breakage during drawing, but also were liable to breaking, jamming and clogging during sharpening. Finally, the sharpeners heretofore known were subject to the accumulation of filings from the lead, with the result that these filings were usually transferred by the sharpened pencil to the drawing to smudge the drawing.

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Although many attempts were made to overcome the foregoing difliculties and other disadvantages of the prior art sharpeners, none, so far as I am aware, was completely successful when carried into practice on a commercial scale.

Accordingly, it is an object of my invention to provide a pencil sharpener adapted for one-handed operation without twisting of the pencil.

Another object of my invention is the provision of a pencil sharpener especially adapted to sharpen replaceable leads held in mechanical, shouldered lead holders of the type used by draftsmen.

A still further object of the invention is the provision of a sharpener for draftsmens leads for use with a shouldered lead holder, designed to relieve stress on the lead during sharpening.

The invention also contemplates the provision of a pencil sharpener so constructed and arranged as to avoid jamming or clogging of the lead or the filings from the lead.

Still another object of the invention is provision of a sharpener for draftsmens leads for use with a shouldered lead holder and adapted automatically to adjust to various lengths of lead protruding from the holder.

Yet a further object of my invention is the provision of a sharpener for draftsmens leads for use with a shouldered lead holder, which will be self-aligning to compensate for leads not inserted precisely along the longituidnal axis of the sharpener.

My invention also contemplates provision of a sharp.- ener for draftsmens leads for use with a shouldered lead holder, permitting use of shorter lengths of lead protrude ing from the holder, but without sacrificing the desired de-. gree of taper imparted to the lead.

Another object of the invention is the provision of a pencil sharpener which will impart a novel shape to the pencil point so that the point will be desirably strong and at the same time have the desired degree of taper.

A further object of my invention is the provision of a pencil sharpener having novel arrangements for collecting and disposing of filings removed from the pencil lead.

Finally, it is an object of my invention to provide a pencil sharpener which will be simple and inexpensive to manufacture, easy to operate and to keep clean, and which will be rugged and durable in use.

Other objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure l is a longitudinal cross-sectional view of a pencil sharpener according to my invention, showing the parts in the position assumed when a lead holder is removed from the sharpener after the lead has been sharpened;

Figure 2 is a view similar to Figure 1 but showing only the upper portion of the device of my invention, with an unsharpened lead about to be inserted;

Figure 3 is a view similar to Figure 2 but showing the arrangement and function of the parts during the sharpening operation; and

Figure 4 is an enlarged plan view of the sharpening means of my invention.

Referring now to the drawings in greater detail, I have shown a pencil sharpener indicated generally at 1, comprising an outer hollow, cylindrical sleeve or casing 3 and a first inner hollow, cylindrical sleeve 5 disposed concentrically within casing 3 and adapted for axial sliding and rotative movement within casing 3. .A continuous spiral groove 7 is formed within the contour of the inner cylindrical wall of casing 3; and a pin 9 or other projection is mounted on the outer cylindrical surface of first inner sleeve 5 and received within groove 7 so as to guide sleeve 5 for axial spiral movement relative to casing 3. First resilient means for urging sleeve 5' toward one end of casing 3 are provided, comprising a coil compression spring 11. Mounted on the end of sleeve 5 adjacent the end of easing 3 toward which the sleeve is urged is a sharpening means 13, for sharpening pencil points, as will be described in greater detail. A screwthreaded annular retaining cap 15 is screwed onto that end of casing 3 to retain sleeve 5 against endwise outward displacement.

A filings collector for filings removed from the pencil point by sharpening means 13 is provided, comprising a second'inner hollow, cylindrical sleeve 17, open at its upper end as seen in Figure 1 and mounted concentrically within but. spaced inwardly from the inner cylindrical wall of casing 3 and received at its upper'end slidably within first inner sleeve 5. Sleeve 17 is mounted at its lower end on a screw-threaded plug 19 which is received in a screw-threaded adaptor ring 21 mounted on the lower end of casing 3. Spring 11 is disposed about sleeve 17 in the space between sleeve 17 and easing 3, and abuts at its lower end against a shoulder of adaptor ring 21 and at its upper end against a washer 23 by which it is spaced from sleeve 5. l As perhaps best seen in Figure 4, sharpening means 13 comprises an annular ring 25 which is coaxial with the axis of spiral movement of sleeve 5 and is provided with a plurality of holes 27 and a plurality of spacer lugs 29 by which it is spaced from the upper end of sleeve 5 as seen in Figure 1. Ring 25 is provided with a beveled inner edge 31 which is conical and has the shape of a truncated cone. Set in the inner edge of annular ring 25 is a plurality of radially inwardly directed cutting blades 33 which extend toward but terminate short of the axis of spiral movement of sleeve 5 and sharpening means 13. Each blade 33 is provided with an inclined cutting edge 35 which extends upwardly and radially outwardly. Cutting edges 35 define elements of an inverted cone inasmuch as corresponding points on all of the edges 35 are disposed at the same elevation and same radial distance from the axis of spiral movement.

Mounted on the underside of cutting blades 33 is. a cylindrical sharpening element 37 having attachment on its upper face with each cutting blade 33. Thus, in addition to their cutting function, cutting blades 33 serve as a spider beneath which sharpening element 37 is suspended. A passageway'39 extends through element 37 from the side to which blades 33 are attached, to the opposite side of element 37. Passageway 39 terminates on the side to which blades 33 are attached in an opening which is circular and concentric with the axis of spiral movement. The lower edges of cutting edges 35 are. coterminous with passageway 39. Passageway 39 is straight and terminates on the underside of element 37 in a circular opening which is eccentric with regard to the axis of spiral movement. Thus, passageway 39 is inclined to the axis of spiral movement; and that axis passes through one point on the marginal edge of the lower terminus of passageway 39. Element 37 may be of abrasive material bonded together, or may be provided with other means for abrading a pencil point, such as serrations 41 extending longitudinally of the passageway. It should be noted that the least figure of rotation generated by any element of the roughly cylindrical side wall of passageway 39 will be a slender cone generated by the middle serration 41 as seen in Figure 4. Hence, it will be apparent that serrations 41 need be supplied only vertically medially as seen in Figure 4. The upper surface of element 37 is conically beveled in the same direction as edge 31 of ring 25, but is not necessarily parallel to edge 31.. In this way, a substantially uniform cross-sectional area of opening between element 37 and ring 25 is provided, through which filings may freely pass. It should also be noted that although only a relatively minor portion of the side wall of passageway 39 will contact a pencil lead to abrade the same, passageway 39, which is of uniform cross-sectional area throughout its length,

' provides a substantial free space through which filings may fall interiorly of element 37. It should particularly be noted that the inclination of passageway 39 is different from that of cutting edges 35. The angle of inclination of cutting edges 35 relative to the axis of spiral movement is substantially greater than the angle of inclination of passageway 39 relative to that axis, with the result that a pencil point will be cut with portions of different inclination.

Means are provided for mounting sharpening means 13 on sleeve 5 for axial sliding movement but against rotation relative to sleeve 5, comprising a plurality of headed pins 43 passing through holes 27 and fixed in the annular end flange of sleeve 5. A coil compression spring 45 is disposed about each pin 43 between the head of pin 43 and ring 25 to urge sharpening means 13 toward the axial opening 47 in the upper end of sleeve 5. The marginal edges of opening 47 are defined by an annular floating bushing 49 mounted coaxially in the upper end of sleeve 5 for free axial rotation relative to sleeve 5. Bushing 49 is provided with a beveled upper inner edge for contact with beveled shoulder 51 of a shouldered lead holder 53 of the type adapted releasably to retain a draftsmans lead 55 The operation of the device of my invention isas follows:

When a pencil is inserted in the device from the position shown in Figure 2, initial contact will be between unsharpened lead 55 and sharpening means 13. Means 13 will be depressed relative to sleeve 5 against the action of compression spring 45, but will not rotate relative to the lead and hence will not yet perform any cutting function. The nextcontact will be between shoulder 51 of lead holder 53 and floating bushing 49, at which time shoulder 51 will seat in bushing 49 in the manner shown in Figure 3. Upon further pushing of the pencil, shoulder 51 will bear against bushing 49 and depress sleeve 5, causing sleeve 5 to spiral downward under the influence of groove7 and pin 9. Sleeve 5 and cutting means 13 will 7 spiral downward together as a unit; and lead holder 53 and bushing 49 will move axially downward together as Hence, sleeve Swill tum a unit but without rotation. relative to bushing/49 and sharpening means 13, resiliently held in contact with the end of lead 55 by springs 45, will rotate, relative to lead 55. Initially, the rotation of sharpening means 13 relative to lead 55 in contact with the end thereof will cause cutting edges 35 to cut an annular conical shoulder about the end of lead 55. However, when this shoulder is completely out, the central portion of lead 55 radially inward from this shoulder will start down passageway '39 and be shaped by abrading contact with serrations 41. These serrations 41, the

medial one of which describes a figure of revolution com-- prising a slender cone as described above, will impart that same figure of rotation to the lower end of lead 55; until the lead is fully sharpened. The fully sharpened lead will have the configuration seen in Figures 1 and 3 to comprise a conical shoulder 57 and a substantially narrower conical point 58. Inasmuch as the axis of spiral movement passes through one point on the marginal edge of the lower opening of passageway 39, and the medial serration 41 terminates downwardly at that point, conical point 58 will be formed over the entire length of passageway 39. In this way, the most eflicient use of sharpening element 37 will be made.

Lead holder 53 may be reciprocated axially any number of times to complete the sharpening operation; and since the change in pressure resulting from change in direction will be borne entirely by shoulder 51 of the by. shoulder 51 to cause-sleeveand sharpening means 13 to move spirally downward. In this way, byfar the greatest part of the strain is removed from the lead itself and transferred to the lead holder. Moreover, it should be noted that the shoulder of the lead holderwill' not be scored by the rotative movement of sleeve 5; since the shoulder bears on bushing 43 whichdoes not rotate ormove relative to shoulder 51-, but which enjoys relative rotational movement with sleeve 5.

It should further be noted that the resilient mounting of sharpening means 13 on pins 4 3 and springs 45 enables. the sharpening means automatically toadjust to any length of lead which may happento protrude. from holder 53. Thus, it is notnecessa-ry to adjust thelength of protruding lead before beginning the sharpening operation. It should also be noted; that the free sliding movement of sharpening means 13 on pins 43 enables a certain amountof side play so that the sharpening means will be self-aligning with the lead in its inserted position.

Moreover, it must be pointed out that filings cut by cutting edges 35- cannot clog or jam the device, since they have free passageway between cutting blades. 33 through the space between opposed. conical facesof beveled edge'31'of ring 25 and sharpening element. 37; Furthermore, filings cut by sharpening element 37 cannotclog or jam the device, since passageway'39' is effectively open throughout its length and is disposed in such a novel and distinctive manner that no portion of narrow conical point 55 except the very top portion will fill the entire crosssection of passageway 39 at any stage of the sharpening operation. A further novel feature of the structure defining passageway 39 is that it is of constant cross-sectional area throughout its length whereas pencil point 58 is of decreasing cross-sectional area from top to bottom thereof, so that the free space in passageway 39 increases toward the bottom of the passageway. The advantage of this arrangement is that the upper portion of passageway 39 need handle the filings from only the upper portion of conical point 58, while the lower portion of the passageway must handle the filings from the entire length of conical point 58 and thus requires a greater free space. It should also be noted that filings falling from sharpening means 13 will be readily accumulated in sleeve 17, which may when filled be readily unscrewed for removal and emptying, and which when in place also provides an inner guide means for slidable sleeve 5 as well as a retainer and positioning means for maintaining coil spring 11 coaxial with the axis of sliding movement and hence generally aligned with the contour of sleeve 5.

Finally, it should be noted that the distinctively unique shape imparted to the sharpened lead, as seen in Figures 1 and 3, provides all the strength of a squat, stubby point with the desirable drawing properties of a narrow, finely tapered point. Moreover, the particular configuration of lead point there shown also enables enjoyment of the advantages of a finely tapered point without the provision of an excessively long length of lead protruding from the holder, as had heretofore been necessary.

Thus, from a consideration of the foregoing disclosure, it will be obvious that I have achieved all of the initially recited objects of my invention.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

I claim:

1. A pencil sharpener comprising a hollow, cylindrical outer casing, a first hollow, cylindrical sleeve axially slidable within said casing, a coil compression spring in said casing resiliently urging said first sleeve toward 6 one end of said casing, sharpening means mounted theend of'said first sleeve adjacent said oneend of said casing; and a filings collector comprising a second hollow, cylindrical sleeve mounted onthe other end of; said casing andextending concentrically into said first sleeve and concentric with but spaced inwardly from the inter-i'or wallof said casing, said first sleeve being slidable in the. space between said casing and said second sleeveand said spring being disposed in said space and acting between said other end of said casing and the other end of said first sleeve.

2. A sharpener for draftsmans leads for use with a shouldered lead holder, comprising a hollow, cylindrical outer casing, a hollow, cylindrical inner casing axially and" rotatably slid'abl'e within said outer casing, one of said casings having a spiral groove in the cylindrical wall thereof adjacent the other of said casings, and the other of said casings having a projection on the cylindrical wall thereof adjacent said one casing, said projection extending-into said spiral groove to guide said inner casing for spiral sliding movement relative to said outer casing, resilient-means urging; saidinner casing toward one end of said outer casing, an annular floating bushing mounted on the end of said inner casing adjacent said one. end of said outer casing, said annular bushing being mounted co axially withsaidinner casing for free axial rotation relativeto said inner casing, and sharpening means mounted onsaid inner casing inwardly of said bushing and fixed against rotation relative to said inner casing, so that when a shouldered lead holder is pushed axially into said sharpener, the shoulder of the lead holder will engage with said floating bushing to slide said inner casing spirally relative to said outer casing without movement of said bushing relative to said shoulder and said sharpening means will rotate relative to said shouldered lead holder to sharpen the lead.

3. A sharpener for draftsmans leads for use with a shouldered lead holder, comprising an elongated outer casing and an inner casing, means guiding said inner casing for spiral sliding movement within said elongated outer casing, first resilient means urging said inner casing toward one end of said outer casing, said inner casing having an axial opening in the end thereof adjacent said one end of said outer casing, sharpening means in said inner casing, means mounting said sharpening means on said inner casing for sliding movement axially of said inner casing and said opening, and second resilient means urging said sharpening means toward said opening, so that when a shouldered lead holder is pushed axially into said sharpener, the shoulder of the lead holder will engage with the marginal edges of said opening to slide said inner casing spirally relative to said outer casing, and said sharpening means will resiliently adjust to the length of the lead and rotate to sharpen the lead.

4. The invention of claim 3, in which said mounting means for said sharpening means comprises a plurality of pins mounted on the inside of said inner casing parallel to the direction of axial movement of said inner sleeve, said sharpening means being slidably mounted on said pins.

5. The invention of claim 4, in which said second resilient means comprises a plurality of coil compression springs, one disposed about each said pin on the side of said sharpening means opposite said opening.

6. The invention of claim 3, in which said marginal edges of said opening are defined by an annular floating bushing mounted coaxially on said end of said inner casing for free axial rotation relative to said inner casing, said shoulder resting on said bushing during operation of said sharpener to avoid movement of said bushing relative to said shoulder.

7. A pencil sharpener comprising an elongated support; sharpening means mounted on said support for spiral movement relative to said support; and means resiliently urging said sharpening means in one axial direction of 7 ment, said passageway terminating on the side of said sharpening element adjacent said cutting blades in a first opening coaxial with said axis of spiral movement, said passageway terminating on the opposite side of said sharpening element in. a second opening, said axis of spiral movement passing through one point on the marginal edge of said second opening, and said cutting blades having cutting edges inclined radially outward away from said sharpening element. 7 8. The invention of claim 7, in which the side of said sharpening element adjacent said cutting blades is beveled radially outward away from said cutting edges.

v9. The invention of claim 8, in which said inner edge of said ring is beveled in the same direction as said side of said sharpening element adjacent said cutting blades.

. 10. The invention of claim 7, in which the angle of inclination of said passageway to said axis is less than the angle of inclination of said cutting edges to said axis.

11. The invention of claim 7, in which the said passageway is of uniformficross-sectional area throughout, 7

means comprising a sharpening element having a passageway therethrough inclined to the axis of spiral movement of said sharpening vmeans, said passageway terminating on one side of said sharpening element in a first opening coaxial with said axis of spiral movement, said passageway terminating on the opposite side of said sharpening element in a second opening, said axis of spiral movement passing through one point on the marginal edge of said second opening.

13. The invention of claim 12, in which said passageway is of uniform cross-sectional area throughout its length.

References Cited in the file of this patent UNITED STATES PATENTS Weathers et al Feb. 10, 1948

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