US2179140A - Pencil sharpener - Google Patents

Description

Nov. 7, 1939. E. 1.. THEOBALD PENCIL SHARPENER Filed June 15, 1938 2 Shets-Sheet 1 11W NTOR. wufv 4.

flax 6W ATTORNEY Nov. 7, 1939. 1 THEQBALD 2.179.140

PENCIL SHARPENER Filed June 15, 1938 2 Sheets-Sheet 2 N VEN TOR.

ATTORNEY Patented Nov. 7, 1939 PENCEL SHARPENER Edgar L. Theobald, Oakland, Calif. Application June 15, 1938, Serial No. 213,779

11 Claims.

This invention relates to a pencil sharpener.

The object of the present invention is generally to improve the construction and operation and to augment the functions of pencil sharpeners; to provide a mechanical device which is capable of handling pencils of all types and diameters such as refill-pencils, wood or papercovered pencils, colored pencils, etc.; to provide a pencil sharpener which will produce either a chisel point or the ccnventionalround sharpened 'point; to provide a. pencil sharpener that is motor driven and totally enclosed to catch and temporarily retain the graphite dust, wood or other material removed from pencils during the sharpening operation; to provide a pencil sharpener employing motor driven high-speed discs constructed of or covered with an abrasive material; to employ discs of this character which are arranged singly or in pairs and whichpresent beveled opposed abrasive surfaces between which the end or point of the pencil to be sharpened is introduced; to provide a mounting and drive for discs of this character which permits the discs when arranged singly or in pairs to be driven in the same direction; to provide abrasive discs or a combination of discs which are individually driven; to provide individual mount- I ings for the abrasive discs which permit movement of the discs to and away from each other; and further, to provide a magnetic pullto yieldingly resist separation of the discs and to return them to a normal position towards the end of eachoperation, a movement that may be augmented-by spring means provided at the outer ends of both shafts' The pencil sharpener is shown by way of illustration in the accompanying drawings in which- .Fig. 1 is a central vertical longitudinal section of the pencil sharpener; I 1

Fig. 2 isacross-section taken on line I III of Fig. 1;

r Fig. 3 is a horizontal section of the motor F and a portion of the housing enclosing the same;

Fig. 4 is a plan View of the pencil sharpener; and.

Fig. 5 is a wiring diagram showing the manner in which the switch, the plug connection and the reception of a drawer t and above the drawer sufficient space for a series of grinding or cutting discs. The brackets also form asupportfor a pair of electric motors E and F which are secured to the brackets by bolts 5. The bolts extend completely through the motors and the end plates C and D, and as such, first serve the function of securing the motors to the brackets, and secondly, that of securing the end plates and the housing to the base.

Secured by set screws or other means on the inner end of each rotor shaft are hub members 6 and 6a, and secured thereto or formed integral therewith are discs 7 andla which are covered with an abrasive material such as carbide .bf silicon, carborundum, aluminum oxide or the like, cemented to cloth or leather. The'adjacent faces of the discs I and la are beveled or flared away from each other as shownin Fig. l, and

the angle formed between the flaring faces may be varied to the degree of taper desired on a pencil point. One of the hubs is externally threaded as shown at 8 to receive and secure the hub of a third disc 9. -Flaring facesof a somewhat smaller angle are formed between this disc and the adjacent disc 7, and these faces are also coveredwith an abrasive which is intended for the purpose of sharpening leads of refillpencils and the like. Afourth disc i0 is secured to the hub 6a. This disc may be constructed of steel, and the face la is provided with radially disposed cutting teeth for the purpose of sharpening certain colored pencils containing a parafiine base. However, the face llla may, if desired, be covered with a coarse abrasive, as thiswill accomplish substantially the same results.

By referring to Fig. 2, it will be noted that two openings l2 and M are formed in the housing, and that said openings align with the space formed between the discs l and la. The opening i2 is of a size to receive pencils of standard diameter. The second opening I4 is provided to accommodate pencils of slightly larger diameter. Openings l5 and i6 are also provided, the opening' it registering with the space formed between the discs '8 and 9-for the sharpening of refillpencils, and the opening it with the face ma. which is provided with cutting teeth or a coarser abrasive, preferably for sharpening colored pencils. The several openings just referred to may be radially disposed with relation to the centers of the discs or they may be slightly offset to As all kinds of individuals are liable to operate machines of this character, such individuals might be referred to as skilled and unskilled, an unskilled person being one who has had no experience with the operation of this or similar grinding machines. Such an unskilled person, when inserting a pencil, is liable to force it inwardly between the discs more rapidly than the wood and graphite are being cut away, and it is accordingly essential that the discs should separate with relation to each other when subjected to such conditions, as there would otherwise be a tendency to overload and stall the motors whereby the discs are driven, which would stop all operation. In the present instance, motors of the induction type are employed. The rotors l8 and I9 which drive the shafts I8a and iSa are arranged out of center with respect to their stators and normally tend to align themselves in the magnetic field produced by the stators 20 and 2|, but when a pencil is inserted between the discs I and la and tends to force them apart or away from each other, the rotors and the shafts upon which they are mounted will move longitudinally in the bearings 30 and 40 and outwardly with relation to the stators 20 and 2!. Such movement is, however, magnetically resisted; hence, there is a yielding resistance to a separation of the discs 1 and la, but this resistance is most desirable under the circumstances previously described, and upon it depends the smooth operation of the machine, as it greatly assists in preventing the overloading of the motors, and as it provides just the right amount of a yielding working pressure for best operating results.

In addition to the magnetic resistance, the outer ends of the shafts l8a. and I911 are rounded or provided with thrust ball bearings 24 which engage plates 25 placed in each end of the housing. Behind these plates are blocks of sponge rubber 26 or the like, said blocks of sponge rubber and the plates 25 being mounted in cap bearings 21 which are screwed into the opposite end plates D and C. These may be screwed inwardly or outwardly and as such may place any end thrust desired on the rotor shafts. Hence when the abrasive discs and 1a are subjected to forces which tend to separate them, such forces are resisted, not only by the magnetic pull exerted by the concerted action of the rotors and the stators of the respective motors, but also by the compression action of the rubber blocks 26. The two thrust bearings described also provide a desirable means of aligning the abrasive discs in regard to their respective openings and furthermore exert a cushioning effect should any longitudinal oscillations develop in the shafts. v

When referring to Fig. 1 it will be noted that a V-shaped deflector 28 is placed centrally of the drawer 4, that is, midway between its ends. This deflector extends from end to end of the drawer and, by utilizing the air current coming from the V-shaped opening between the high-speed discs, it serves the purpose of deflecting dust, wood and other material removed during the sharpening operation, causing said material to be thrown into opposite sides of the drawer, thereby preventing it from piling up or building up around the abrasive or cutting discs.

The drawer is provided with .a knob 28a, and by exerting a pull, the drawer may be removed through an opening in one side of the housing (see Fig. 2) and the dust and other foreign permit the abrasive to cut with a shearing action.

matter collected may thus be removed from time to time.

For the purpose of convenience, a cord connector 35 is placed in one end of the housing so that a plug such as shown at 36 may be plugged in and the pencil sharpener connected to any available electric system. A switch 31 is similarly placed in the opposite end of the housing to make or break the circuit through the motors.

Due to the fact that pencils produced by different manufacturers vary slightly in diameter, it is desirable to provide some of the openings indicated at M, I5 and I6 with adjustable sleeves to take care of such variations. The sleeves are best illustrated at M in Figs. 1 and 2. The upper and lower ends of the sleeves are provided with exterior tapering shoulders 42 and 43 which are engaged by internally tapered upper and lower bush-.

ing members 44 and 45. These bushings are screwed into the housing, and as the sleeves are longitudinally slotted at a plurality of points and from opposite ends, movement of the bushings by rotation thereof will cause the internal portions to engage the external tapered ends of the bushings and thereby cause contraction of the same, such contraction making it possible to adjust the sleeves to snugly fit pencils of varying diameters. Such adjustment retains the pencils against play or wobble when inserted through the openings, and at the same time retains the pencils in a position which is central between the abrasive discs, thereby assuring a perfect point, whether the point is round or chisel-shaped.

The opening it, as previously stated, aligns with the cutting face 10a. This face isparticu-a larly intended for cutting heavy wood or papercovered pencils, colored pencils containing paraii'ine, and the like. The opposed faces I and la may vary with respect to the grade of abrasive material employed; for instance, one face may u ple and substantial in construction. Everything is arranged for rapid manipulation and for the convenience of the operator. Compactness and a balanced symmetrical design are made possible by the use of two motors, while also simplifies the general construction and makes it possible to employ the magnetic pull of the stators to resist separation of the abrasive discs. A single motor having the same horsepower as the two small motors now employed could obviously be used, but that would materially increase the height and width of the housing, and unbalance the design due to the great diiference in weight between'the motor on one end and the abrasive equipment on the other end. It would furthermore complicate the structure and the mechanism as the abrasive The necessary joining ofseveral Wires is done on the bottom face side of the base plate, thus avoiding any possibility of arcing or sparking due to loose wire connections, etc. This is important, as'the graphite and wood dust represent a highly explosive material.

Having thus described my invention, what I claim and desire to secure by Letters Patent is: l. A pencil sharpener comprising a housing, a pair of motors enclosed by the housing, a pair of abrasive discs, each disc independently driven by a motor, said discs being closely spaced but having their adjacent faces beveled away from each other, with the greatest spacing between their peripheral edges, to form a tapering pencil point, an opening formed in the housing to permit a pencil to be inserted between the opposed beveled discs, said discs being movable to and away from each other to permit separation when a pencil is inserted between the discs, and magnetic means resisting separation of the discs and restoring the discs to normal position when a pencil is removed.

2. A pencil sharpener comprising a housing, a pair of motors enclosed by the housing, a rotor and shaft in each motor and having a limited longitudinal movement therein, a pair of abrasive discs, each disc independently driven by its rotor and shaft, said discs being closely spaced but having their adjacent faces beveled away from each other, with the greatest spacing between their peripheral edges, to form a tapering pencil point, an opening formed in the housing to permit a pencil to be inserted between the opposed beveled discs, said discs, rotors and shafts being movable to and away from each other to permit separation when a pencil is inserted between the discs, and means for resisting separation of the discs, rotors and shafts and restoring the discs to normal position when a pencil is removed.

3. A pencil sharpener comprising a housing, a pair of motors enclosed by the housing, a pair of abrasive discs, each disc independently driven by a motor, said discs being closely spaced but having their adjacent faces beveled away from each other, with the greatest spacing between their peripheral edges, to form a tapering pencil point, an opening formed in the housing to permit a pencil to be inserted between the opposed beveled discs, said discs being movable to and away from each other to permit separation when a pencil is inserted between the discs, and combined resilient and magnetic means resisting separation of the discs and restoring the discs to normal position when a pencil is removed.

4. A pencil sharpener comprising a housing, a pair of motors enclosed by the housing, a stator and rotor in each motor, a shaft for each rotor, a pair of bearings in each motor in which the respective shafts and the rotors carried thereby are journaled, and in which they are longitudinally movable, said longitudinal movement of the shafts and rotors being resisted by the magnetic field produced by the stators, an abrasive disc secured on the inner end of each rotor shaft, said discs being closely spaced but havingtheir adjacent faces beveled away from each other, with the greatest spacing between their peripheral edges, to form a tapering pencil point, and an opening formed in the housing to permit a'pencil to be inserted between the opposed beveled discs.

5. A pencil sharpener comprising a housing, a pair of motors enclosed by the housing, a stator and rotor in each motor, a shaft for each rotor, a. pair of bearings in each motor in which the respective shafts and the rotors carried thereby are journaled, and in which they are longitudinally movable, a resilient end-thrust bearing adjacent the outer end of each rotor shaft to resist longitudinal movement of the shafts, an abrasive disc secured on the inner end of each shaft, said discs being closely spaced but having their adjacent faces beveled away from each other, with the greatest spacing between their peripheral edges, to form a tapering pencil point, and an opening formed in the housing to permit a pencil to be inserted between the opposed beveled discs.

6. A pencil sharpener comprising a base plate, a pair of offset brackets, one adjacent each end of the base plate, an electric motor supported by each offset bracket, a housing supported by the base and enclosing the motors, an end plate at each end of .the housing, bolts extending through the offset brackets, the motors and the end plates, to secure the motors to the brackets and the end plates to the housing, a shaft in each motor, an abrasive disc secured on the inner end of each shaft, said discs being closely spaced but having their adjacent faces beveled away from each other to form a tapering pencil point, and an opening formed in the housing to permit a pencil to be inserted between the opposed beveled faces of the discs.

'7. A pencil sharpener comprising a base plate, a pair of offset brackets, one adjacent each end of the base plate, an electric motor supported by each offset bracket, a housing supported by the base and enclosing the motors, an end plate ateach end of the housing, bolts extending through the offset brackets, the motors and the end plates, to secure the motors tothe brackets and the end plates to the housing, a shaft in each motor, an abrasive disc secured on the inner end of each shaft, said discs being closely spaced but having their adjacent faces beveled away from each other to'form a tapering pencil point, an opening formed in the housing to permit a pencil to be inserted between the opposed beveled faces of the discs, and a drawer insertable through an opening in the side of the housing, said drawer being supported by the base between the offset brackets, and adapted to receive material ground off pencils.

8. A pencil sharpener comprising a base plate,

apair of offset brackets, one adjacent each end of the base plate, an electric motor supported by each offsetbracket, a housing supported by the base and enclosing the motors, an end plate at each end of the housing, bolts extending through the offset brackets, the motors and the end plates, to secure the motors to the brackets and the end plates to the housing, a shaft in each motor, an abrasive disc secured on the inner end of each shaft, said discs being closely spaced but having their adjacent faces beveled away from eachother to form a tapering pencil point, an opening formed in the housing to permit a pencil to be inserted between the opposed beveled faces of the discs, a drawer insertable through an opening in the side ofthe housing, said drawer being supported by the base between the offset brackets, and adapted to receive material ground oif pencils, I and a deflector disposed centrally of the drawer and extending from end to end thereof,

to deflect the ground-off material into oppositesides of the drawer.

9. In a pencil sharpener of the character described a main housing, a motor housing enclosed by the main housing, said motor housing having a rotor and a shaft and the rotor and shaft having a limited longitudinal movement in the motor housing, an abrasive disc secured on the motor shaft, said disc having a beveled surface to engage and point the end of a pencil, said disc, rotor and shaft moving longitudinally within the motor housing when pressure is exerted by a pencil against the beveled surface of the disc, and magnetic means resisting longitudinal movement of the rotor, shaft and disc.

10. In a pencil sharpener of the character described a main housing, a motor housing enclosed by the main housing, said motor housing having a rotor and a shaft and the rotor and shaft having a limited longitudinal movement in the motor housing, an abrasive disc secured on the motor shaft, said disc having a beveled surface to engage and point the end of a pencil, said disc, rotor and shaft moving longitudinally within the motor housing when pressure is exerted by a pencil against the beveled surface of the disc, and combined resilient and magnetic means resisting longitudinal movement of the rotor shaft and disc.

11. In a pencil sharpener of the character described a main housing, a motor housing enclosed by the main housing, said motor housing having a. rotor and a shaft and the rotor and shaft having a limited longitudinal movement in the motor housing, an abrasive disc secured on one end of the motor shaft, said disc having a beveled surface to engage and point the end of a penciLsaid disc, rotor and shaft moving longitudinally within the motor housing when pressure is exerted by a pencil against the beveled surface of the disc, a resilient thrust bearing engaging the opposite end of the motor shaft to resist longitudinal movement, and magnetic means to resist longitudinal movement.

EDGAR L. THEOBALD.

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