US3903558A

US3903558A - Eraser strip and chuck assembly for motor driven erasing machines

Info

Publication number: US3903558A
Application number: US304354A
Authority: US
Inventors: Clifford E Anderson
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-11-06
Filing date: 1972-11-06
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09

Abstract

An eraser strip and chuck assembly for motor driven erasing machines having a chuck tube for receiving eraser strips and having collet chuck means for releasably securing the eraser strips in immovable assembly with the rotatable chuck and chuck tube of the erasing machine. The strips of erasing material define gas passage means or, in the alternative, cooperate with the chuck tube and collet mechanism of the erasing machine to define gas passage means, for conducting a compressed gaseous medium to the contact point between the eraser strip and the surface being erased for the purpose of cooling the contacting surfaces and blowing erasure particles away from the immediate area being erased. The configuration of the eraser strip may also aid in the mechanical erasing process.

Description

United States Patent Anderson *Sept. 9, 1975 [54] ERASER STRIP AND CHUCK ASSEMBLY 1548436 [2/1970 Henrich 4. 15/339 X 3,806,977 4/1974 Anderson 1 r t 4 1 1 15/344 X MACHINES Primary ExammerHarvey C. Hornsby [76] Inventor: Clifford E. Anderson, 6440 Amman, Moore Hillcrofi, Houston, Tex. 77036 Notice: The portion of the tenn of this l ABSTRACT patent subsequent to Apr. 30. 1 1 An eraser strip and chuck assembly for motor driven has been disclaimed. erasing machines having a chuck tube for receiving [22] Filed: No 6 19.72 eraser strips and having collet chuck means for releasably securing the eraser strips in immovable assembly [2 [1 Appl No.: 304,354 with the rotatable chuck and chuck tube of the erasing machine The strips of erasing material define gas pas- [52] Us. Cl 15/353; 15/344 sage means or. in the alternative, cooperate vvith the [51] Im- (12 H A47L 5/24; B43L IQ/OU chuck tube and collet mechanism of the erasing ma- [58] Field of Search 1. 15 353 344 Chm define gas Passage means for conducmg a compressed gaseous medium to the contact point be- [56] References Cited tn'een the eraser strip and tthe surface being erased f0;

t e purpose 0 coo mg t e contacting sur aces an UNITED STATES PATENTS blowing erasure particles away from the immediate 1,66Lll1 2/1928 Coy l5/368 X area being erased. The fi ti f the eraser l,932,6ll /1933 Whalen l5/4l9 X Strip y also aid in the mechanical erasing process 2330.954 lO/l943 Cotera /153 X 3,254,629 6/1966 Dicorte .1 15/330 X 10 Claims, 12 Drawing Figures l :l j 1. l 1

PATENTED SEP 9 5 SHEET 2 OF 3 PATENTED P 1975 SHEET 3 OF 3 F/GJO ERASER STRIP AND CHUCK ASSEMBLY FOR MOTOR DRIVEN ERASING MACHINES FIELD OF THE INVENTION This invention is related generally to the use of motor driven erasing machines for erasing undesirable markings from a surface and, more specifically, is directed to strips of erasing material and chuck mechanisms for gas blowing erasing machines that may cooperate to define gas passage means through which pressurized gas may flow for the purpose of cooling and blowing erasure particles away from the immediate area being erased.

BACKGROUND OF THE INVENTION Mechanically driven erasing machines, such as those driven by both AC and DC electric motors, have been utilized for many years. Erasing machines of this nature will generally incorporate a motor drive mechanism that is connected to a chuck tube and collet chuck mechanism that receives and releasably secures a generally cylindrical strip of erasing material, typically referred to as an eraser strip, in immovable relation to the chuck and chuck tube. Most powered erasing machines are electrically energized, but it is not intended to limit this invention to erasing machines of the electrically energized type. Upon manual manipulation of an on-off switch, the erasing machine, which is typically adapted to be hand held, may be energized to cause rapid rotation of the eraser and may be manually brought to bear upon a surface to erase undesirable markings therefrom.

As an erasing operation is conducted, the surface being erased is eroded to some extent and erasure particles become separated from the eraser and become deposited on the surface along with particles eroded from the surface, thereby contaminating the surface. The particles will generally become electrically charged during the erasing process which causes the particles to adhere tenaciously to the surface. Periodically, it is necessary, in order to facilitate good visibility of the surface being erased, for the operator of the machine to cease the erasing operation and remove the erasure particles from the surface by means of a brush or through the use of any other acceptable erasure particle removal device. Ceasing the erasing operation in this manner and periodically removing the erasure particles from the surface, obviously detracts from the commercial effectiveness of the erasing operation, because of the amount of time utilized in brushing the erasure particles or grit away from that portion of the surface being erased.

Another problem, encountered in the use of mechanical erasing machines, concerns the generation of heat between the rapidly rotating eraser and the surface being erased. When a rotating eraser is brought to bear upon a paper surface, to remove pencil or ink lines therefrom, a draftsman, utilizing the machine, must exercise great care to prevent the contact area from becoming hot enough to burn through the paper as well as becoming hot enough to cause deterioration of the eraser. When erasing ink or pencil lines from a plastic film surface, a craftsman may not be allowed to utilize a mechanical erasing device because the film is so susceptible to burn through due to heat deterioration of the film. It is quite difficult to erase markings from a plastic surface without generating enough heat to burn through the surface. As the draftsman applies the rotat ing eraser to the surface it is typically necessary for the machine to be periodically lifted from the surface for cooling, which, of course, adds time to the erasing operation and detracts from the commercial feasibility thereof.

Heat generated during an erasing operation may cause burnishing or slight discoloration of a paper surface, being erased, and may detract from the ability of the paper to receive ink or pencil markings after being erased. It may be necessary, after utilizing a mechanical eraser, for erasing pencil or ink lines on paper, to clean the erased surface with a manually applied eraser before applying ink or pencil lines thereto. Of course, between the mechanical and manual erasing operations, it is necessary to brush away the erasure particles. Considerable time may therefore be expanded in the drafting and erasing operation which is, of course, undesirable.

Another factor that may detract from mechanical erasing operation, is the amount of wear that occurs on rotating erasers because of the great amount of heat that is generated. Frequently, a rapidly rotating eraser will become sufficiently heated during an erasing operation that the eraser material will break down and crumble away quite rapidly. Heat deterioration of the eraser in this manner obviously substantially increases the cost of the erasing operation, as well as substantially increasing the amount of eraser particles that be come deposited on the surface being erased, which particles of course must be brushed away before a drafting operation can be continued.

A draftsman drawing with pencil or ink on a paper surface will typically employ the following erasing sequence during drafting operations:

1. Pick up erasing machine.

2. Erase.

3. Lay erasing machine down.

4. Pick up brush.

5. Brush erasure particles away from the erasing area and inspect erasure.

6. Lay brush down.

7. Pick erasing machine up again.

8. Touch up incomplete erasure or erase over lines again to improve quality of erasure.

9. Lay erasing machine down.

10. Pick up brush.

ll. Brush erasure particles away from erasing area and reinspect erasure.

l2. Lay brush down.

13. Repeat steps 7-12 if necessary.

14. Begin drawing again.

It is therefore a primary object of the present invention to provide a novel eraser strip and chuck mechanism for a mechanically driven erasing machine that provides the draftsman with the capability of utilizing the following sequence during erasing operations:

1. Pick erasing machine up.

2. Erasing and inspecting erasure simultaneously, because grit or erasure particles will have been removed from the surface being erased during application of the eraser to the surface.

3. Lay erasing machine down.

4. Begin drawing again.

It is a further object of the present invention to provide a novel eraser strip and chuck mechanism for a mechanically driven erasing machine that lends the erasing machine the capability of entraining a flow of compressed gaseous medium, such as air, on the surface being erased, immediately adjacent to the point of contact between the eraser strip and the surface, which flow of gaseous medium is sufficiently great to blow erasure particles away from the area being erased, thereby, providing the draftsman with good visibility of the area being erased at all times.

It is an even further object of the present invention to provide a novel eraser strip and chuck assembly for mechanically driven erasing machines having the capability of developing a flow of gaseous medium for achieving cooling of the contact area between the eraser and the surface being erased, thereby preventing burning of the surface being erased and preventing excessive crumbling or erosion of the eraser material during the erasing operation.

Among the several objects of the present invention is noted the contemplation of a novel eraser strip and chuck assembly for mechanically driven erasing machines which, when utilized, promotes optimum erasing at nominal eraser cost by preventing excessive wear of erasers during an erasing operation.

It is an even further object of the present invention to provide a novel eraser strip and chuck assembly for mechanically driven erasing machines that employs a supply of compressed gaseous medium and defines gas passage means through which gaseous medium is con ducted from the supply of gaseous medium and is entrained on the surface being erased for cooling and particle blowing purposes.

An even further object of the present invention contemplates the provision of a novel eraser strip and chuck assembly for mechanically driven erasing machines that may define plural gas passages along the eraser strip from which pressurized gaseous medium may flow for purposes of cooling and removal of erasure particles.

It is also an object of the present invention to provide a novel eraser strip for motor powered erasing machines which provides a cross-sectional configuration that aids in mechanical erasing of markings from a surface.

Other and further objects, advantages and features of the invention will become obvious to one skilled in the art upon an understanding of the illustrative embodiment about to be described and various advantages, not referred to herein, will occur to one skilled in the art upon employment of the invention in practice.

SUMMARY OF THE INVENTION The present invention is directed to an eraser strip and chuck assembly for motor powered erasing machines incorporating a source of gaseous medium under pressure for the purpose of cooling the eraser strip and the surface being erased and for the purpose of blowing erasure particles away from the immediate area being erased.

The erasing strip may have an external or internal configuration that defines an air passage along the length of the eraser strip, which air passage may conduct a flow of gaseous medium and direct the flow upon the surface being erased. The eraser strip, received within the erasing machine, may be of generally cylindrical cross section and may be provided with an elongated groove in the outer periphery thereof, which groove may be disposed in generally parallel relation with the axis of the eraser strip. The elongated groove may cooperate with a chuck seal device and with a chuck tube structure of the erasing machine to define an elongated air passage through which air may flow during operation of the erasing machine, thereby causing a flow of compressed air to be directed to impinge upon the surface being erased. The chuck seal device effectively prevents air from dissipating from the air passage through slots that are typically defined between the segments of collet type chucks.

Where eraser strips are employed that cooperate with the structure of the erasing machine to define an air passage, the eraser strip itself may be of any suitable configuration defining a single air passage or plural air passages.

In an alternative embodiment of the present invention the eraser strip may be provided with a passage extending therethrough which passage may be adapted to receive an air supply conduit extending from the air supply of the erasing machine structure. The air passage in the eraser strip will conduct a flow of gaseous medium from the air supply conduit to an outlet defined by the air passage at the lower extremity of the eraser strip.

In a further alternative embodiment of the present invention a collet chuck mechanism may be employed having one or more collet segments having elongated grooves formed therein, which grooves cooperate with the cylindrical peripheral surface of an eraser strip to define one or more gas passages through which compressed gaseous medium may be conducted from the interior of the erasing machine and may be directed toward the area of contact between the eraser strip and the surface being erased.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the manner in which the above recited advantages and objects of the invention are attained, as well as others, which will become apparent, can be understood in detail, more particular description of the invention, briefly summarized above, may be had by reference to the specific embodiments thereof, which are illustrated in the appended drawings, which drawings form a part of this specification. It is to be understood, however, that the appended drawings illustrate only typieal embodiments of the invention and therefore, are not to be considered to be limiting of its scope, for the invention may admit to other equally effective embodiments.

In the Drawings:

FIG. 1 is an elevational view with parts thereof broken away and illustrated in section showing an electrically energized erasing machine having an air supply mechanism connected thereto and incorporating a conventional chuck tube and chuck collet mechanism receiving an eraser strip constructed in accordance with the teachings of the present invention.

FIG. 2 is an elevational view with parts thereof broken away and shown in section presenting an electrically energized erasing machine incorporating a chuck tube, chuck collet and eraser strip assembly constituting a modified embodiment of the present invention.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2 and illustrating the eraser strip, the chuck collet and the chuck collet seal in detail.

FIG. 4 is a sectional view taken along line 4-4 in FIG. I and illustrating the eraser strip, chuck collet and air supply passage in detail.

FIGSv 5 through 9 are sectional views illustrating eraser strips representing modified embodiments of the present invention.

FIG. 10 is a fragmentary sectional view of a chuck and chuck seal assembly representing a modified embodiment of the present invention and illustrating the relationship of the chuck and chuck seal assembly to a generally cylindrical strip of erasing material being supported by the chuck assembly.

FIG. 11 is a transverse sectional view taken through the collet chuck and chuck seal assembly ofa modified embodiment of the present invention, illustrating the gas passage defining relationship between elongated grooves defined in one or more of the segments of the collet chuck mechanism and the cylindrical peripheral surface of an eraser strip supported by the chuck mechanism.

FIG. 12 is a transverse sectional view taken through the collet chuck and chuck seal assembly of a further modified embodiment of the present invention illustrating gas passages defined in each segment of a three segment collet chuck mechanism.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings and first to FIG. I, there is shown an electrically energized erasing machine, generally at It), having an AC or DC energized electric motor 12 disposed within a housing 14. The rotating armature 16 of the motor 12 may be non rotatably secured to a chuck shaft 18 that is supported for rotation relative to the housing 14 by upper and

lower bearings

20 and 22, respectively. A chuck mechanism illustrated generally at 24 may be threadedly connected to the lower extremity of the chuck tube 18, as shown, or may be connected in any other desirable manner for non'rotatable relationship with the chuck tube. The chuck mechanism 24 may, if desired, be of the collet type, where a plurality of segments 26 may be drawn into engaging and holding relationship with a strip of erasing material by a collet lock ring 28 or by any other suitable mechanism capable of achieving locking of the collet mechanism in the closed or strip holding position thereof.

An erasing machine, capable of directing a flow of gaseous medium against the surface being erased, for the purpose of cooling and blowing erasure particles, may conveniently take the form set forth in US. patent application Ser. No. 303,981 of Clifford E. Anderson filed Nov. 6, 1972, or in the alternative may take any other suitable form, as desired. The supply of gaseous medium, which may be referred to as an air supply, may be remotely located and connected to the erasing mechanism by a supply conduit or, if desired, may be physically attached to the erasing machine in driven relation therewith, as shown in FIGS. 1 and 2. The air supply mechanism 30 is shown to incorporate a con ncctor shaft 32 that may be received in fixed and sealed relation to the chuck shaft 18 in any desirable manner and may be provided with a gas passage 33 for the purpose of introducing a flow of gaseous medium, such as air, from the air supply mechanism into the chuck tube.

The collet chuck assembly 24 is adapted to receive and become locked into releasable assembly with any suitable strip of erasing material of generally cylindrical configuration. Also a non-cylindrical eraser strip may be held by the collet chuck as long as at least some points defined by the cross-sectional configuration of the eraser strip may be engaged by the gripping surfaces of the collet chuck mechanism.

In providing a flow of gaseous medium, such as air, for the purpose of cooling the contact area between the eraser and the surface being erased and for providing a fiow of air at sufficient velocity for blowing away erasure particles that have become deposited on the surface being erased, it will be desirable to provide an air supply passage having an outlet opening as near the point of contact, between the eraser and the surface being erased, as is conveniently possible. Accordingly, a strip of eraser material may be employed to define or to cooperate with other structure to define an air passage extending through or along the length of the eraser strip. One suitable eraser strip, having an air passage defined therein, may conveniently take the form illustrated in cross-section at 34 in FIG. 4, where the eraser strip 34 is shown to be provided with a generally cylindrical periphery 36 disposed for engagement by the segments 26 of the collet chuck assembly 24. The eraser strip 34 may be provided with an axial bore 38 through which may extend an air supply conduit 40 that is secured at the upper extremity thereof to the connector shaft 32. Compressed air, provided by the air supply mechanism 30, will flow through the air sup ply conduit 40 and will exit from the outlet opening 43 defined by the lower extremity of the eraser strip 34.

It is obvious that a reduction in the cross-sectional dimension of the eraser strip, caused by the axial bore 38, will inherently weaken the eraser strip. To prevent the eraser strip from becoming excessively weak, the air supply conduit 40 may extend downwardly through the collet chuck mechanism 24 as far as is necessary to provide the degree of internal rigidity that is necessary for providing the eraser strip with desired structural integrity. It is also desirable that the air supply conduit 40 be of sufficient length to maintain engagement within the bore 38 of the eraser strip 34, even when the eraser strip becomes quite short, due to erosion thereof during the erasing process. When it is desired to replace a worn eraser strip or an eraser strip that is not desirable for the particular erasing operation involved, it is simply necessary to move the locking ring 28 upwardly as shown in FIG. 1, thereby releasing the clamping relation of the segments 26 of the chuck assembly 24 with the outer periphery 36 of the eraser strip. After the chuck assembly has become unlocked, the draftsman, utilizing the machine, may simply grasp the lower extrcmity of the eraser strip 34 and withdraw it from the machine. The air supply conduit 40 then will be protruding slightly beyond the lower extremity of the chuck assembly. A new eraser strip may be installed into the machine simply by bringing the axial bore 38 of the eraser strip into receiving relation about the air supply conduit 40 and then simply pushing the eraser strip into the chuck tube 18 until the lower extremity of the eraser strip is properly exposed for erasing. The chuck assembly then may be manipulated to the locked position thereof by moving the locking ring 28 downwardly and causing a camming action with tapered cam surfaces 42 defined on each of the chuck segments 26 to force the gripping surfaces of the segments into tight engagement with the outer periphery of the eraser strip.

"in. w- 1 u. leum.

As illustrated in FIG. 2, an erasing machine may be provided that may include a collet chuck assembly and chuck tube mechanism that cooperate with a strip of erasing material to define an air passage along the strip of erasing material for the purpose of cooling and blowing erasure particles. The erasing machine may be identical with respect to the erasing machine illustrated in FIG. 1, as shown by corresponding reference numerals, with the exception that it may not be necessary to provide an air supply conduit to establish fluid communication between the air supply mechanism 30 and the air passage along the eraser strip. Air in this case will merely be introduced from the air supply passage 33 of the connector element 32 into the chuck tube 18.

In order to conduct a flow of gaseous medium from the chuck tube along the eraser strip, it will be practical to define some structural irregularity in the eraser strips or in the chuck tube in order for the eraser strip to cooperate with the chuck tube to define an elongated air passageway. It will not generally be practical to deform the chuck tube along the length thereof because such structural deformation would interfere with the fit of the chuck tube with other mechanical parts of the erasing machine. Moreover, the expense of deforming the chuck tube in this manner will ordinarily be sufficiently great as to render it impractical.

The other alternative, therefore, is to provide an eraser strip having an external configuration which, when disposed in assembly with the chuck tube and chuck structure of the erasing machine, will define at least one and perhaps a plurality of elongated air passages extending along the full length of the eraser strip.

An eraser strip, according to the present invention, may conveniently take the form illustrated in FIGS. 2, 3 and where an eraser strip 44 is illustrated having a generally cylindrical peripheral surface 46. The eraser strip 44 may be deformed in such manner as to define an elongated groove 48 having an arcuate cross section defined by an arcuate wall 50. Cooperation of the arcuate wall 50 with the outer cylindrical surface 46 of the eraser strip effectively defines opposed undercut chipping edges 52 and 54 that engage the surface being erased and tend to chip away markings from the surface, depending upon the direction the strip is located. For example, assuming the eraser strip to be rotated clockwise as shown by the arrow in FIG. 5, the chipping edge 54 will be leading while edge 52 will be trailing. The chipping edge 54 will therefore be caused by the direction of rotation to engage and chip the markings from the surface being erased. The erasing action therefore combines the effect of a chipping action with the simple abrasive effect of the rotating eraser strip. If the eraser strip is inserted with the other end inwardly then edge 52 becomes the chipping edge.

As indicated above, the collet chuck mechanism will be composed of a plurality of chuck segments 26 that may be cammed into friction supporting relation with the outer surfaces of an eraser strip by a locking ring 28, cooperating with tapered cam surfaces 42. Because the collet chuck mechanism employs a plurality of segments, it is obvious that a plurality of grooves or slots will be defined one between each of the pairs of segments. If an eraser of the configuration set forth in FIG. 5 were employed with a collet chuck mechanism of ordinary construction, air flowing through the air supply passage, defined by the cooperating relation of the groove 48 with the wall structure of the collet segments, would be allowed to flow outwardly and become dissipated to a large extent through the slots of the chuck mechanism.

According to the present invention a means for preventing dissipation of air through the slots of a conventional collet chuck mechanism, may conveniently take the form, illustrated in FIGS. 2 and 3, where a chuck seal element, illustrated generally at 56 in FIG. 3, may be interposed between the segments 26 of the collet chuck assembly and the peripheral surfaces of the eraser strip 44. The chuck seal element 56 may be of generally cylindrical cross-section and may be provided with an external configuration cooperating with the internal surfaces 60 of the segments 26.

It should be noted that the sealing element 56 stops short of the lower extremity of the chuck segments 26 and therefore, a small amount of gas dissipation will take place if the eraser strip should be assembled so that one of the external grooves in the eraser strip connects to one of the spaces between the chuck segments 26. Tests have shown that the flow of air will not be materially impaired by the small amount of air flow that is dissipated below the chuck seal and that air that does flow through the slots will be directed to sweep the surface being erased and therefore will aid in removal of erasure particles from the surface. If it is desired to eliminate any leakage whatever through the slots defined between the collet segments, such may readily be accomplished by providing a lower resilient skirt as an extension of chuck seal element 56 shown in broken lines at 62 that may define generally cylindrical inner and

outer surfaces

64 and 66, respectively.

The outer cylindrical surface 66 may be disposed for engagement by the inner cylindrical surface 68 of each of the segments 26. The inner cylindrical surface 64 may extend the full length of the chuck seal element and may receive the outer cylindrical wall 46 of the eraser strip 44 in loose relation therewith. The chuck seal 56 including the thick upper portion 58 and the thin flexible lower portion 62 is completely impervious to the passage of air and therefore will provide a barrier to prevent dissipation of air from the groove 48 of the eraser strip through the slot defined by the collet chuck mechanism.

If the chuck seal is provided witha lower flexible skirt portion, it is obvious that the eraser strip received by the erasing machine must be of smaller diameter than eraser strips of standard size in order to compensate for the thickness of the flexible skirt. It is considered most practical, however, to utilize eraser strips of standard size especially in view of the fact that careful location of the groove 50 relative to a collet segment, as shown in FIG. 5, will eliminate any dissipation of the flow of air below the chuck seal.

After an eraser strip has been inserted into the chuck tube l8 of the erasing machine in the manner set forth in FIG. 2, the locking ring 28 of the collet chuck mechanism may be moved downwardly as shown in FIG. 2 toward the free extremity of the chuck mechanism, thereby camming the segments 26 toward the strip of erasing material for the purpose of gripping the same. If the chuck seal shown in full line at 58 is employed, the segments will be cammed into holding engagement with the eraser strip. If the chuck seal incorporates a flexible skirt portion as shown in broken line at 62 in FIG. 3, manipulation of the chuck mechanism by movement of the locking ring 28 will cause the thin flexible portion 62 of the chuck seal 56 to become deformed to the extent that it is urged into friction tight gripping relation with the outer cylindrical wall 46 of the eraser strip, thereby positively securing the eraser strip in releasable assembly with the collet chuck mechanism and positively supporting the eraser strip during the erasing operation. The chuck seal 56 may be composed of any suitable resilient material, such as any one of a number of commercially available resilient plastic materials which materials have sufficient memory to allow the resilient skirt portion thereof to revert to its normally uncollapsed condition upon release of the collet chuck mechanism.

An eraser strip for use in conjunction with an erasing machine, such as illustrated in FIG. 2, may take any number of different external configurations without departing from the spirit and scope of the present invention. As illustrated in FIG. 6, an eraser strip 70 may be provided with a generally cylindrical external peripheral surface 72 and may have a groove 74 of generally rectangular cross-sectional configuration formed therein. The groove 74 will cooperate with the wall structure defined by the chuck tube 18 and the chuck seal element 56 to define an air passage along the entire length of the eraser strip.

An eraser strip need not be provided with a groove in order to cooperate with the internal surfaces of the chuck tube and seal element to define an air passageway. As illustrated in FIG. 7, an eraser strip 76 is shown, having a generally cylindrical external surface 78 that is intersected by an elongated planar surface 80. When an eraser strip, constructed in accordance with FIG. 7, is received within an erasing machine, the generally planar elongated surface 80 will be disposed in chordal relationship with the inner peripheral surfaces defined by the chuck tube and chuck seal elements. The space defined by this chordal relationship will define elongated air passage extending along the full length of the eraser strip.

It may be desirable to provide a plurality of air passages along the eraser strip to evenly distribute air for purposes of cooling and blowing erasure particles. As illustrated in FIG. 8, an eraser strip 82 may be provided having a generally cylindrical outer surface 84 with a plurality of elongated generally parallel grooves 86 defined in evenly spaced relation about the eraser strip, which grooves may cooperate with the wall structure of the chuck tube and chuck seal elements to define a plurality of elongated air passages that direct a flow of air to the contact point between the eraser and the surface being erased.

Plural air passages may be defined by an eraser strip of non-circular cross section. essentially as shown in FIG. 9, where an eraser strip 88 is shown that is of generally pentagonal cross-sectional configuration, which configuration is defined by a plurality of elongated planar surfaces 90 disposed in chordal relation to an imaginary cylinder defined by generally parallel lines 92 established by the intersecting planar surfaces 90. The skirt portion 62 of the chuck seal element 56, if utilized, will engage the eraser strip 88 along the lines 92 defined by the intersecting planar surfaces 90, thereby supporting the eraser strip in releasably locked assembly with the collet chuck mechanism of the erasing ma chine.

It is obvious that strips of erasing material may be provided with any number of different external configurations that cooperate with the chuck tube and the chuck seal element of an erasing machine to define one or more air passages along the length of the eraser strip. It is intended, therefore, that the particular eraser strip configurations, illustrated in FIGS. 5-9, be considered merely exemplary of the cooperative relationship that may be established between any eraser strip and the chuck mechanism of an erasing machine, which relationship defines at least one and perhaps a plurality of air passageways along the length of the eraser strip.

It may be desirable to provide a chuck mechanism for a motor powered erasing machine that may cooperate with a conventional cylindrical eraser strip to define at least one and perhaps a plurality of air passages through which air may flow from a compressor connected to the erasing machine and may be directed to the area of contact between the rotating eraser and the surface being erased. A chuck mechanism for accomplishing this feature may conveniently take the form illustrated in FIGS. 10 and 11 where a chuck mechanism, illustrated generally at 94, is shown to be connected to the chuck tube of a motor powered erasing machine in conventional manner. The chuck mechanism 94 may incorporate a plurality of collet segments 96 some or all of which may be internally machined to define elongated passageways 98, as shown in FIG. 11 the chuck assembly may include four collet segments that may be urged into assembly with a conventional eraser strip of cylindrical configuration by a locking ring 100 disposed for camming engagement with tapered surfaces 102 defined on the collet segments.

As explained above, the collet segments will typically fit together in such manner as to define a plurality of slots through which air may escape or dissipate as it is pumped toward the lower extremity of the eraser strip. It is therefore desirable to provide a means for preventing dissipation of air through the collet slots and, according to the present invention, such means may conveniently take the form illustrated in FIGS. 10, 11 and 12 where a sealing device, illustrated generally at 104, is shown to be disposed circumferentially about the collet chuck mechanism. The sealing device 104 may incorporate an annular body portion 106 of impervious nature to which body portion may be fixed or integrally formed a plurality of slot sealing partitions 108 adapted to be received in the slots between the collet segments 96. The sealing element 104 may be composed of any one of a number of commercially available resilient materials that may yield quite readily to allow the same to be received in assembly with the collet segments. Rigid or semi-rigid materials will also function efficiently if the collet segments are placed in assembly with the sealing element before the collet mechanism is assembled to the chuck tube of the erasing machine.

With reference now to FIG. 12, which is a sectional view taken through a collet chuck mechanism, representing a modified embodiment of the present invention, it is quite clear that a collet chuck mechanism, having three interrelating segments 112, may be employed in similar manner as the structure illustrated in FIG. 11. One or more of the collet segments may include a groove 114, machined or otherwise formed therein, which cooperates with a conventional eraser strip 116 of cylindrical configuration to define an air passage extending along the eraser strip and directing a flow of pressurized air at the contact point between the eraser strip and the surface being erased, for the purpose of cooling and for removal of erasure particles. A sealing element, illustrated generally at 118, may be assembled to the collet chuck mechanism 110 and may incorporate a body portion 120 of generally cylindrical configuration having slot sealing partitions 122 fixed to or formed integrally with the body portion 120 and serving to seal the slots defined by the collet mechanism to prevent undesirable dissipation of air.

It is therefore apparent that, within the scope of this invention, conventional cylindrical eraser strips may be received by a specifically constructed chuck mechanism to define air passages through which air may flow for cooling and for removal of erasure particles. The chuck mechanism cooperates with the eraser strip to define one or more air passageways directing a flow of air or other compressed gaseous medium toward the surface being erased. A collet chuck mechanism of this nature, although being of substantially more expensive nature, as compared to the collet chuck mechanism illustrated in FIGS. 3, 4 and 5, will allow use of conventional cylindrical eraser strips such as are presently commercially available at relatively low cost in erasing machines incorporating an air flow system.

In view of the foregoing, it is apparent that l have provided a novel eraser strip hand chuck assembly for motor driven erasing machines, which assembly is capable of defining at least one elongated air passageway either along or through the length of an eraser strip, supported by the erasing machine, for the purpose of directing a flow of air, or other compressed gas, to impinge upon the surface being erased, for the purpose of cooling and for removal of erasure particles. The eraser particles, even though electrically charged to the extent that the same would normally adhere tenaciously to the surface being erased, will be quite easily blown away from the immediate area being erased, thereby giving the draftsman a clear view at all times of the area being erased and eliminating the necessity for frequent brushing of the surface for inspection purposes. The flow of air, directed against the surface being erased, effectively cools both the surface and the abrading tip of the eraser to such extent that burnishing of the surface or heat erosion or crumbling of the eraser material is effectively retarded. Moreover, through use of eraser strips constructed in accordance with the present invention, the speed of the erasing operation will be enhanced substantially because it will not be necessary for the draftsman to bear down with the eraser upon the surface to insure complete erasing. The draftsman will be enabled to scrutinize the erasing operation at all times, because the surface being erased will be clean and the draftsman will be enabled to accurately determine the degree of force that is necessary for optimum erasing.

Eraser strips of many different configurations may be manufactured simply and inexpensively through the use of simple and inexpensive dies through which eraser material is forced.

It is therefore seen that my invention is one well adapted to attain all of the objects and advantages, hereinabove set forth, together with other advantages, which will become obvious and inherent from a description of the apparatus itself. It will be understood that certain combinations and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the present invention.

As many possible embodiments may be made of this invention, without departing from the spirit or scope thereof, it is to be understood that all matters hereinabove set forth, or shown in the accompanying draw ings, are to be interpreted as illustrative, and not in any limiting sense.

I claim:

1. An eraser strip and chuck assembly for motor powered erasing machines having means for conducting a flow of pressurized gas to a surface being erased for cooling and cleaning purposes, said eraser strip and chuck assembly comprising:

a source of pressurized gas;

a chuck tube being connected in driven relation to the motor of the erasing machine, said chuck tube receiving said pressurized gas;

a collet mechanism being disposed at the lower extremity of said chuck tube; and

a strip of erasing material being removably disposed within said chuck tube and collet mechanism said eraser strip having at least one elongated groove defined therein and extending along the length thereof, said groove cooperating with said chuck tube and said collet mechanism to define gas passage means between the exterior surface of said strip of erasing material and said chuck tube and collet mechanism, said gas passage means terminating at an outlet opening near the tip of said strip of erasing material and directing the flow of gas from said gas passage means against the surface being erased, said collet mechanism establishing releasable gripping relation with said strip of erasing material and confining the flow of said pressurized gas to said gas passage means.

2. An eraser strip and chuck assembly as recited in claim 1:

said groove being of arcuate cross-sectional configuration.

3. An eraser strip and chuck assembly as recited in claim 1:

collet seal means interposed between said collet mechanism and said eraser strip and preventing dissipation of gas from said gas passage means through said collet mechanism.

4. An eraser strip and chuck assembly as recited in claim 3:

said collet seal means having a yieldable portion, said yieldable portion being urged by said collet mechanism into releasable friction locked engagement with said strip of eraser material.

5. An eraser strip and chuck assembly as recited in claim 1:

said eraser strip defining at least one chipping edge for engaging the surface to be erased.

6. An eraser strip and chuck assembly for motor powered erasing machines having means for conducting a flow of pressurized gas to a surface being erased for cooling and cleaning purposes, said eraser strip and chuck assembly comprising:

a source of pressurized gas;

a collet mechanism being disposed at the lower extremity of said chuck tube;

a strip of erasing material being removably disposed within said chuck tube and collet mechanism, said strip of erasing material having a generally cylindrical peripheral surface; said collet mechanism defining at least one elongated internal groove, said groove cooperating with said cylindrical surface of said strip of erasing material to define gas passage means; and collet seal means disposed exteriorly of said collet mechanism and preventing dissipation of gaseous medium through said collet mechanism. 7. An eraser strip and chuck assembly as recited in claim 6:

seal tabs being disposed internally of said collet mechanism and being received within said slots of said collet mechanism to seal said slots against dissipation of gaseous medium therethrough. 8. In combination, a strip of eraser material and a motor powered rotary erasing machine:

said erasing machine having a chuck tube for receiving the strip of erasing material and having a collet chuck mechanism at the lower extremity of the chuck tube for releasably securing said eraser strip in immovable relation with said chuck tube and collet chuck mechanisms; and

an elongated body of erasing material adapted to be received within said chuck tube of said erasing machine said body of erasing material being formed to define groove means along the entire length thereof, said groove means cooperating with said chuck tube and collet chuck mechanism to define air passage means between said chuck tube and collet mechanism and said strip of eraser material.

9. The combination of claim 8 wherein:

said groove means is of arcuate cross-sectional configuration.

10. The subject matter of claim 9 wherein:

said body of eraser material is of generally cylindrical configuration.

Claims

1. An eraser strip and chuck assembly for motor powered erasing machines having means for conducting a flow of pressurized gas to a surface being erased for cooling and cleaning purposes, said eraser strip and chuck assembly comprising: a source of pressurized gas; a chuck tube being connected in driven relation to the motor of the erasing machine, said chuck tube receiving said pressurized gas; a collet mechanism being disposed at the lower extremity of said chuck tube; and a strip of erasing material being removably disposed within said chuck tube and collet mechanism said eraser strip having at least one elongated groove defined therein and extending along the length thereof, said groove cooperating with said chuck tube and said collet mechanism to define gas passage means between the exterior surface of said strip of erasing material and said chuck tube and collet mechanism, said gas passage means terminating at an outlet opening near the tip of said strip of erasing material and directing the flow of gas from said gas passage means against the surface being erased, said collet mechanism establishing releasable gripping relation with said strip of erasing material and confining the flow of said pressurized gas to said gas passage means.

2. An eraser strip and chuck assembly as recited in claim 1: said groove being of arcuate cross-sectional configuration.

3. An eraser strip and chuck assembly as recited in claim 1: collet seal means interposed between said collet mechanism and said eraser strip and preventing dissipation of gas from said gas passage means through said collet mechanism.

4. An eraser strip and chuck assembly as recited in claim 3: said collet seal means having a yieldable portion, said yieldable portion being urged by said collet mechanism into releasable friction locked engagement with said strip of eraser material.

5. An eraser strip and chuck assembly as recited in claim 1: said eraser strip defining at least one chipping edge for engaging the surface to be erased.

6. An eraser strip and chuck assembly for motor powered erasing machines having means for conducting a flow of pressurized gas to a surface being erased for cooling and cleaning purposes, said eraser strip and chuck assembly comprising: a source of pressurized gas; a chuck tube being connected in driven relation to the motor of the erasing machine, said chuck tube receiving said pressurized gas; a collet mechanism being disposed at the lower extremity of said chuck tube; a strip of erasing material being removably disposed within said chuck tube and collet mechanism, said strip of erasing material having a generally cylindrical peripheral surface; said collet mechanism defining at least one elongated internal groove, said groove cooperating with said cylindrical surface of said strip of erasing material to define gas passage means; and collet seal means disposed exteriorly of said collet mechanism and preventing dissipation of gaseous medium through said collet mechanism.

7. An eraser strip and chuck assembly as recited in claim 6: seal tabs being disposed internally of said collet mechanism and being received within said slots of said collet mechanism to seal said slots against dissipation of gaseous medium therethrough.

8. In combination, a strip of eraser material and a motor powered rotary erasing machine: said erasing machine having a chuck tube for receiving the strip of erasing material and having a collet chuck mechanism at the lower extremity of the chuck tube for releasably securing said eraser strip in immovable relation with said chuck tube and collet chuck mechanisms; and an elongated body of erasing material adapted to be received within said chuck tube of said erasing machine said body of erasing material being formed to define groove means along the entire length thereof, said groove means cooperating with said chuck tube and collet chuck mechanism to define air passage means between said chuck tube and collet mechanism and said strip of eraser material.

9. The combination of claim 8 wherein: said groove means is of arcuate cross-sectional configuration.

10. The subject matter of claim 9 wherein: said body of eraser material is of generally cylindrical configuration.