US2709990A - Pencil sharpener - Google Patents

Description

J. W. POYSA PENCIL SHARPENER `lune 7, 1955 Filed July 23, 1951 1m mme. Joy/v /L/ Pos/.sw

United. States Patent Patented June 7, li'

2,709,990 PENCIL SHARPENER .lolut W. Poysa, Burbank, Calif. Application July 23, 1951, Serial No. 238,139 8 Claims. (Cl. 12ii 96) This invention relates to pencil sharpeners. While the invention is adapted for use with Sharpeners for pencils in which the lead is encased in a wooden stock, asfto some of its features, it is particularly adapted to Sharpeners for artists or other pencils of the type in which the lead is mounted within a metal or other cylindrical holder and is longitudinally adjustabiy movable within the holder so that it may be projected outwardly `from the holder a little at a time as the pencil is used.

In sharpening pencils of any kind and particularly the relatively elongated and more loosely secured leads oT pencils of the artists type, the lead must be properly supported transversely against the cutting surface and must be rotated relative to the cutting surface while it is thus supported and is being acted upon by the cutting surface. lhere must be proper correlation between the supporting pressure which acts perpendicularly to the cutting surface, the tangential force which is exerted upon the surface of the lead by the cutting surface, and the torsional stress applied to the lead, which latter is a function ot' the speed with which the lead is relatively rotated on the axis with respect to the cutters. The lead must be relatively, rapidly rotated to insure even cutting of the outer surface of Ythe lead at all points ol its circumference. The lead is usually manually held stationary while being acted upon by the cutters.

A familiar and well known sharpening operation for pointin tools or other objects is that in which the article is hel, in the hand of the operator against a rotating cylindrical cutting surface, such as a grind stone and slowly and evenly turned by hand and at the same time pressed by hand against the cutting surface. lt is an object of this invention to provide a mechanical means for thus holding the lead against a rotating cutting surface by a gentle even pressure and at the same time steadily and slowly rotating the lead relatively to the axis of rotation of the cutting surface at a uniform speed while it is' being sharpened. The lead is manually held relatively stationary in the pencil Sharpener. Thus the lead is ground to a smooth surface point without breakage and in a rapid eilicient manner.

ln the pencil Sharpener of this invention, as in many other known pencil Sharpeners, two conically shaped cutting wheels are mounted with their axes parallel to the axis of the pencil on diametrically opposite sides of the pencil and preferably and usually with the axes of the two cutters equidistunt from the axis of the pencil. The cutter wheel shafts rotate in planetary fashion about the pencil as the cutters rotate upon the shafts. ln these known Sharpeners each cutter, both functions as a Sharpener for the lead and also as a support for the other cutter.

lt is also characteristic of these known pencil sharpeners that the two cutters rotate at the same speed and in the same angular direction and therefore exert oppositely directed tangential forces upon the lead. The stationarily held lead is thus subjected to a high twisting or torsional stress, wnich is double the torsional stress to which the lead would be subjected if only one cutter was ernployed. lf, however, as in some of the known pencil Sharpeners, only one cutting wheel is provided, a one sided flexure thrust develops, transversely of the lead which is more apt to break the pencil point.

In a pencil Sharpener constructed in accordance with this invention the two conically shaped cutting wheels are, as stated above, mounted with their axes parallel to the axis of the pencil and in addition to their rotation each on its own axis, are rotated bodily about the axis of the pencil holder so that each cutting wheel abrades the pencil lead on that side of the lead which is diarnetrically opposite to the side which is being abraded by the other cutting wheel; but one or" the wheels is rotated in the pencil Sharpener of this invention at a speed substantially greater than the other, as for instance in a ratio of about two to one. The high speed cutter is relied upon to do most of the abrasive work and the slow speed cutter acts to hold the lead against the high speed cutter and at the same time abrades the surface of the lead to a relatively small degrec. Since it rotates at a lesser speed, the torsional stress applied to the lead is substantially less than where the two cutting wheels are driven at the sante speed.

The ratio speeds of revolution of the high and low speed cutters is preferably such that the speed of the faster cutting wheel is not an integral number multiple of the speed of the slower cutting wheel. lf the speed of the faster wheel were such an integral number multiple of the speed ot the slower wheel any circumferential area of the cutting wheel would contact the lead at the saine circumferential portion thereof for each revolution with the result that if the cuttinfr wheel is out of round at any particular portion of the cutting surface, the lead would be unevenly ground at that point. T his is true because, when constructed in accordance with this invention, the cutting wheels rotate bodily about the lead at a speed of revolution which is controlled by the slowl moving cutting wheel.

lt is therefore an object of this invention to provide a pencil Sharpener with two conically shaped cutting wheels, the speed of the cutting surface of one wheel relatively to the lead being substantially less than the speed of the other cutting surface relatively to the lead.

It is also an object of this invention to provide the pencil Sharpener with two conically shaped cutting wheels, the speed of the cutting surface of one wheel relatively to the lead being greater than the speed of the other cutting surface relatively to the lead in a ratio which is not an integer.

lt is another object of the invention to provide a pencil Sharpener which shall have a rapid abrasive action combined with low torsional stress on the lead. It is still another object to provide a pencil Sharpener which will be compact, inexpensive to manufacture and assemble, and convenient to use.

It is another object of the invention to provide a holding rest for the pencil holding sheath and lead and particularly of an artists type pencil, which shall hold the lead against bending of the lead with respect to its holder while it is being sharpened.

It is also an object of the invention to provide a bearing frame for the cutting wheels which shall hold the cutting wheels with their axes in rigid parallel relation to the axis of the pencil.

Other objects and advantages of the invention will be apparent from a reading of the following specification and claims and from an inspection of the accompanying drawing.

The drawing illustrates one embodiment of the invention. The invention'is not limited to the speciiic forni of this embodiment but includes other specific forms and embodiments which corne within the spirit and scope of the appended claims.

In the drawing Figure l is a perspective view of a pencil Sharpener embodying the invention.

Figure 2 is a central longitudinal vertical sectional view of the Sharpener shown in Figure 1.

Figure 3 is a transverse vertical sectional view' at a reduced scale taken along the lines 3 3 of Figure 2.

Figure 4 is a transverse vertical sectional view at the same reduced scale along the lines 4 4 of Figure 2.

Figure 5 is a transverse vertical sectional view at the saine reduced scale taken along the lines 5 5 of Figure 2.

Figure 6 is a perspective View of the dust shield.

'Figure 7 is a perspective view of the outrigger bearing prece.

A frame 11 of the pencil Sharpener has a base 12 which may have formed therein holes 12a for reception of fastening screws for attaching the frame to a desk or other statlonary object. The frame 11 further comprises a standard 13 and a housing 14, the base, standard, and housing being preferably made of one integral piece of metal.v

The housing 14 is generally cylindrical in shape, having a hub portion 14a, a ring portion 141i,` and a connecting radial flange portion 14C, the ring 14h and the radial ange 14C providing a cup shaped re cess 14d, The ring 14h has a shouldered circular recess 14e at its free end. The recesses 14a' and 14e serve as a mounting chamber for the driving mechanism of the cutter wheels, as will presently appear.

The ring 14h has a shallow annular recess 14f which receives an annular ange 15a of the hood 15. To as semble the hood 15 on the housing 14, the flange 5a is slid longitudinally inwardly over the recessed surface 141 with slots aligned with pins 24 which are rigidly mounted in the ring 14b. When the hood 15 is thrust over the housing 14 to its home position, it is given a slight twist by which the pins 24 are made to engage the hooked ends of the slots 25 locking the hood 15 in its position of assembly on the housing 14, The hood has the shape shown in the drawing, the upper portion of the hood acting as a protector for the moving parts of the pencil Sharpener and the lower portion acting as a receptacle for the particles of lead and other debris resulting from the sharpening operation.

A main shaft 2@ turns in a bearing bushing 21 stationarily secured to the bore of the hub 14n. A crank handle 17 is fastened to the shaft 20 by means of a fastening screw 26, the hub 17a of the crank handle serving to prevent inward longitudinal movement of the shaft 20. A crank handle 18 is fastened to the outer end of the crank by means of a fastening screw 19, which is loosely revolvably disposed in the crank handle, and screw fastened to the outer end of the crank.

The shaft 20 is expanded at its inner end to provide a rotating circular flange 27 upon which are mounted the cutting wheels. This flange 27 prevents outward longitudinal movement of the shaft 20 with respect to the housing 14, The inner end portion of the flange 27 is formed with a recess shaped as shown in Figure 3. It also is formed with two cylindrical sockets which are lined with bearing bushings and 33 respectively.

A shaft 29 turns in the Shaft bearing Sil and a shaft 32 turns in the bearing 33, Each of these shafts has an enlarged central portion designated as 29a and 32a on the drawing, and a reduced portion at each of its ends, one end being revolvably mounted in one of the bearings 30, 33 and the other end having rigidly mounted thereon one of a pair of conically shaped cutting wheels 41, 42.

The shaft 29 has integrally formed thereon a relatively large gear wheel 28 which rotates within the recess on the inner end face of the flange 27 on the shaft 2li as Seen in Figure 3, The shaft 32 has integrally formed thereon a relatively small gear wheel 31 which also rotates in this same recess in flange 27.

The teeth of the gear wheel 23 mesh with the teeth of an internal gear 22 which is seated within the shouldered recess 14e of the housing 14 and is heid against rotation by a pair of fastening screws 23. As the shaft 2t) is rotated when the operator turns the crank 17, the flange 27 carries with it the shaft 29. As the shaft 29 turns about the axis of the shaft 26 it is caused to rotate on its own axis in the opposite direction by the engagement of the gear 2S with the internal gear 22.

The gear wheel 31 is rotated in the same angular direction as the gear 28 by means of a middle gear 39 which rotates on a pin which is press fitted in a socket in the inner end face of the flange 27. The middle gear 39 CJi also meshes with and is driven by the gear 2S. The speed of revolution of the gear wheel 31 is substantially greater than the speed of rotation of the gear wheel 28, preferably in a ratio which is of a fractional character. ln the drawing, for example, the gear wheel 31 rotates twenty times for every eleven revolutions of the gear wheel 28, the ring gear 22 having 72 teeth, the gear wheel 28 having 40 teeth, the middle gear 39 having 2O teeth, and the gear wheel 31 having 22 teeth. A dust shield 54, suitably appertured to t over the shafts 29 and 32 rotates with the shafts and serves to prevent the dust and debris of the cutting wheels from entering between the gear wheels and interfering with their proper meshing.

The outer ends of the reduced portions of shaft 29 and 32 are mounted within bearing bushings 37 and 3S respectively which line a pair of sockets formed in a rotating front bearing fratrie 34. This frame piece 34 rotates with and is secured to the flange 27 by means of rods 35 and 36 which are screw threaded at their rightward end into the flange 27 and are provided at their leftward end with screw heads seated within suitably sized countersunk bores in the front bearing frame as shown in dotted lines in Figure 2. The dust shield S4 is suitably apertured to receive the rods 35 and 36.

The cutter wheels 41 and 42 are shrouded within a double circled recess 44 (see Figure 5) in the frame piece 34. This recess 44 extends from the rightward face of the frame piece 34 at the dust shield 54 to the leftward end of the cutting wheels. The side walls of each circular half portion of this recess 44 extend in parallel lines to the rightward face of the cutting wheels to form two tangentially arranged cylindrical cavities 55 and thence slope conically axially inwardly to the leftward end of the cutting wheels to form conically shaped cavities 56 as shown in Figure 2, to conform to the conical shape of the cutting wheels. The walls of the conically shaped cavities 56 are each cut away at the outermost portion of their respective bores to provide openings 57 to facilitate the discharge of the dust and debris resulting from the abrasion of the lead.

The frame piece 34, which also serves as a cutting wheel cover, is circularly recessed at 49 for the reception of the pencil when it is inserted into the tapered opening 47 between the cutting wheels. The circular side wall of the recess 49 tapers inwardly from the outer end of the hub Sil of the cutting wheel cover 34 presenting in cross section a concave curve. At the inner end of this curved recess, a short circular neck 48 in the frame piece 34 connects the recess 49 with the tapered opening or work rest 47 in the frame piece 34 between the cutting wheels. The curved sides of the recess 49 guide the metallic holder of the pencil lead and seat it in the base of the recess with the lead projecting into the opening or work rest 47.

Shoulders 45 and 46 on shafts 29 and 32 between the lengths of larger diameterand of smaller diameter of these two shafts, space the cutting wheels at a proper distance from the driving gears. The cutting wheels may be drawn up tightly into fixed position on their respective shafts by tightening the screw rods 35 and 36.

When the screw rods 35 and 36 are turned the frame piece 34 is pulled tightly against the dust shield 54 which in turn is pulled tightly against the leftward face of the shaft flange 27. Thus the frame piece 34 and the leftward end bearings of the cutter wheel shafts are held in rigid relation to the shaft 20, the shaft, cutting wheel frame piece, the cutting wheels and the dust shield rotating as one assembly about the shaft axis,

The hood 15 has a circular opening 51 for the accommodation of the leftward projecting end of the hub 50 of the grinding wheel cover.

In the operation of the pencil Sharpener, the pencil is inserted through the recess 49 in the hub 50 of the front bearing frame 34, held against turning, and pressed gently in a rightward direction by the operator with one hand, while with the other hand the crank 17 is turned, rotating the shaft 20 and fiange 27. The gear wheels 28 and 31 revolve on their own axes and also revolve bodily about the axis of the shaft 20 in planetary fashion. The gear wheel 28 revolves about its own axis at a speed of revolution substantially less than that of the gear wheel 31 about its axis, and the cutting wheels 41 and 42 rotate at correspondingly proportional speeds, as for instance in a ratio of ll to 20. The cutting wheels, however, revolve bodily at the same speed about the axis of the shaft 20 which is coincident with the axis of the opening 47 between the cutting wheels. The slow moving cutting wheel 41 holds the lead against the faster moving cutting wheel 42, slowly turning against the lead at the same time; while the cutting wheel 42 rapidly rotates on its axis and performs the major portion of the work of sharpening the lead. Any given point on the faster moving cutting wheel contacts a given radially alined point on the lead, once in every twenty revolutions.

While the invention has been herein disclosed as applied to that type of pencil in which the lead is longitudinally movable in a metal sheathing holder, it is also applicable to pencils in which the lead is encased in a wooden stock. It will be understood that in a pencil Sharpener of the latter type, the cutting wheels will extend outwardly along the wooden stock a distance to plane down the wooden stock in a conical shape aligned with the conical point on the lead. In such Sharpeners it is a known feature of the cutting surfaces to have the abrading surface at the smaller end of the cutting wheels of a character to suitably reduce the size of the wooden stock and the cutting surface at the larger end of the cutting wheels of a character to suitably act upon and reduce the size of the lead point.

I claim:

l. In a pencil Sharpener: a main frame; two axially alined bearing supports mounted on the frame; two cutting wheels rotatably mounted on the supports, longitudinally alined and tapering in the same sense and spaced to receive the pointed end of a pencil at their smaller ends; a rotating shaft mounted on the frame; means for driving the shaft; a first driving wheel rigidly related to a first one of the cutting wheels; power transmitting means connecting the shaft and the first driving wheels designed to give the cutting surface of the rst cutting wheel a linear speed having a rst ratio to the angular speed of the shaft; a second driving wheel rigidly related to a second one of the cutting wheels; power transmitting means connecting the shaft with the second driving wheel designed to give the cutting surface of the second cutting wheel a linear speed having a second ratio to the angular speed of the shaft, one of said ratios being substantially greater than the other.

2. The combination defined in claim l, in which the larger one of said two ratios is not an integral number of times the smaller of said ratios.

3. The combination defined in claim l, in which the diameters of the cutting wheels are equal at corresponding longitudinal positions.

4. The combination defined in claim 3, in which the angular speed of one cutting wheel is not more than threefths of the speed of the other cutting wheel.

5. The combination defined in claim 3, in which the said bearing supports are mounted on a frame rotatably mounted on the main frame, and power transmitting means connecting the shaft and bearing frame for rotating the bearing frame.

6. In a pencil Sharpener: a main frame; a shaft rotatably mounted in the main frame; means for rotating the shaft; a ring gear iixedly mounted on the main frame; a rotatable plate xedly mounted coaxially on the shaft; two inner shaft bearing supports in the plate with their axes parallel to and equidistant radially from the shaft axis; an outrigger bearing piece axially spaced away from and rigidly secured to said plate having two outer shaft bearing supports axially alined with said two inner shaft bearing supports respectively; a pair of shafts each rotatably mounted with respect to a pair of associated ones of said inner and outer bearings, the outrigger bearing piece being secured to the plate by means additional to and independent of said pair of shafts; two outwardly diverging conical cutting wheels mounted on said pair of shafts respectively between said inner and outer bearings, with their corresponding ends in transverse alinement and spaced laterally for sharpening a pencil point; a set of spur gears rotatably mounted on said plate and meshing with said ring gear, two of which spur gears are rigidly related to said cutting wheels respectively.

7. In a pencil Sharpener: a main frame; a shaft rotatably mounted in the main frame; means for rotating the shaft; a ring gear iixedly mounted on the main frame; a rotatable plate iixedly mounted coaxially on the shaft; two inner bearings supported by the plate with their axes parallel to and equidistant radially from the shaft axis; an outrigger bearing piece axially spaced away from and rigidly secured to said plate and supporting two outer bearings axially alined with said two inner bearings respectively; two outwardly diverging conical cutting wheels rotatively supported by said inner and outer bearings, with their corresponding ends in transverse alinement and spaced laterally for sharpening a pencil point, the outrigger bearing piece being secured to the plate by means additional to and independent of said wheel supports for said cutting wheels; a set of spur gears rotatably mounted on said plate at least one of which spur gears meshes with said ring gear, and two of which spur gears are rigidly related to said cutting wheels respectively.

8. In a pencil Sharpener: a main frame; a shaft rotatably mounted in the main frame; means for rotating the shaft; a ring gear xedly mounted on the main frame; a rotatable plate iixedly mounted coaxially on the shaft; two inner bearings supported by the plate with their axes parallel to and equidistant radially from the shaft axis; an outrigger bearing piece axially spaced away from and rigidly secured to said plate and supporting two outer bearings axially alined with said two inner bearings respectively; two outwardly diverging conical cutting wheel assemblies rotatively supported by said inner and outer bearings, with their corresponding ends of the wheels in transverse alinement and spaced laterally for sharpening a pencil point; a set ofspur gears rigidly and coaxially associated with said assemblies and rotatably mounted on said plate at least one of which spur gears meshes with said ring gear, and two of which spur gears are rigidly related to said cutting wheels respectively, the set of spur gears being enclosed in a recess in the outer face of said rotatable plate, the recess being shaped to snugly surround the peripheries of the gears of said gear set, and the recessed portion of the plate extending beyond the outer faces of the gears of the gear set and the outer face of the ring gear lying just inside the outer face of the plate, and the outrigger bearing piece being clamped to the rotating plate by bolts threaded into the outer face of the bearing plate; and a circular dust shield interposed and clamped by said bolts between the outer face of the plate and the inner face of the outrigger bearing piece, said dust shield being apertured to snugly accommodate the cutting wheel assemblies passing therethrough and the said clamping bolts.

References Cited in the ile of this patent UNITED STATES PATENTS 667,173 Whowell Jan. 29, 1901 1,546,538 Fischer July 21, 1925 1,722,771 Spengler July 30, 1929 1,735,638 Cohen Nov. 12, 1929 1,872,476 Loveland Aug. 16, 1932 2,184,476 Blake Dec. 13, 1939 2,545,779 Harrison Mar. 20, 1951

Images