Title:
Erasing tool
United States Patent 2441441


Abstract:
The present invention relates in general to erasing tools and, in particular, to an erasing tool which is arranged to produce a fine stream of air carrying eraser abrasive which is directed against a surface that is to be erased. One of the objects of the present invention is to provide a...



Inventors:
Paasche, Jens A.
Application Number:
US69495346A
Publication Date:
05/11/1948
Filing Date:
09/05/1946
Assignee:
Paasche, Jens A.
Primary Class:
International Classes:
B24C5/02
View Patent Images:
US Patent References:
2305976Pressure gun1942-12-22
2133149Sand blasting mechanism1938-10-11
1730195Sand-blast device1929-10-01
1712804Sand-blast device1929-05-14
0554299N/A1896-02-11



Description:

The present invention relates in general to erasing tools and, in particular, to an erasing tool which is arranged to produce a fine stream of air carrying eraser abrasive which is directed against a surface that is to be erased.

One of the objects of the present invention is to provide a new and improved power eraser which is light in weight and convenient to handle.

Another object of the invention is to provide an improved form of eraser which is capable of cutting lines or dots from a large area by means of a fine jet of compressed air carrying eraser abrasive.

Still another object of the invention is: to provide an improved form of power eraser which is capable of erasing very rapidly and at the same time is adapted to perform delicate erasing operations.

A still further object of the invention is to provide an improved, eraser, of the type_ described, wherein all parts subjected to the stream of air carrying eraser abrasive are especially designed to withstand abrasive action and; are arranged to be replaced readily.

These and other objects of the: invention will appear upon a perusal of the following specification taken in conjunction with the accompanying drawing, wherein: Fig. 1 is an elevational view of the erasing tool of the present invention:; Fig. 2 is an enlarged sectional view of the, erasing tool shown in- Fig. 1; and Fig. 3 is a sectional view, at a further enlarged scale, of a portion of the eraser shown in Fig. 2 taken along the section line 3-3 thereon.

Described briefly, the eraser of the present in,vention comprises a cup assembly in which powdered abrasive is placed and. which is provided with an outlet terminating in-a jet. The;cup assembly includes an inlet through which compressed air is at times admitted. When air is admitted to the cup assembly it creates a fine mist of abrasive which is carried with the air through the outlet and issues from the jet in a fine stream traveling at a high velocity. The cup assembly is attached to a handle provided withi a valve adapted to be operated by the index finger for convenience in operation of the eraser, which- is preferably held in the same manner as: a pencil.

Referring now to the drawing; the cup- assembly in which the abrasive material' is- placed comprises a cylindrical powder cup: 4 havingi a cap 6 threaded thereon at its upper end: andi having a conically shaped portion, at- its lower end: which is threaded on a stem 8. A powder' tube 1.0 extends within and is threaded into the stem 8.

The space between the stem 8 and the powder tube 10 forms a passage through which air is admitted to the powder cup. A cup-shaped deflector 12 is secured to the powder tube 10 at the point where it issues from the stem 8. The lowermost edge of the deflector 12 is spaced a short distance from the upper face of the stem 8 to cause air admitted to the powder cup to traverse a circuitous path in its passage therethrough, and in addition is provided with two or more skewed slots 14 (Fig. 3), which are preferably substantially tangential to the outer diameter of powder tube 10, in order to impart a whirling action to 16 the. air admitted to the powder cup. The upper end of the powder tube 10- is spaced a short distance from the cap 6, which has an adjusting screw (16threaded therein in axial alignment with the powder tube 10. The adjusting screw 16 is provided with a hardened steel cone-shaped insert l8 which matches a hardened steel cylindrical insert 20 secured within powder tube 10 at the upper end thereof. A coil spring 22 maintains tension on adjusting screw 16 to prevent undesired movement thereof.

The: cup; assembly is supported by the stem 8 which extends from a body portion 24 of the eraser. The body portion 24 is provided with a passage 261 communicating with the powder tube 10, at the lower end thereof and with a hardened steel: jet 28- which is secured to the body portion 24 by means of a flanged, nut, 30. The body portion 24 also, includes a chamber 32 and a passage 34 extending from the chamber 32 through the as body portion 24and through:the stem 8.

A second stemr 36 extends from the body portion 24 of the eraser. A valve casing 38 is threaded into the stem 36. The valve casing 38 is provided: with: suitable threads at its lowermost. end; to permit an air hose to be coupled thereto. A. valve; head 40, secured to the lower end, of a: plunger 42; is biasedý upwardly by means of a coil spring 44 extending between the lower end of the plunger 42 and a hollow nut 46 which 41 is threaded into the' valve casing- 38' at its lowermost. end. A. rod 418 extends within a threaded shank-of the valve casing 38 and fits over the end of the valve- plunger 42, The. rod' 48 is terminated at its upper endi by a finger button 50, 80 'by means of which the; valve may be operated to, admit air to) the chamber 32: through a passage 52 extending through the body portion 24 and the stem. 36 froman air hose: (not shown) which is- attached toa the valve casing 38.. A s5 stroke- adjusting nut 54 having a knurled head and having a hollow shank is threaded over the upper end of the threaded shank portion of valve casing 38. The adjustment of nut 54 determines the extent to which the air valve may be opened when the finger button 50 is depressed as far as possible. A collar 56 is forced on the rod 48 to retain the rod 48 and finger button 50 within the stroke adjusting nut 54. A hollow handle 58 is threaded into the body portion 24 of the eraser to enable grasping thereof in the same manner as a pencil is grasped.

The valve head 40 is normally pressed into airtight engagement with the valve casing 38 to prevent entrance of air into the chamber 32.

When the finger button 50 is depressed the valve head 40 is disengaged from the valve casing 38, permitting air to flow from the air hose (not shown) coupled to the valve casing 38, through the hollow nut 46, between the valve head 40 and valve casing 38, through a passage 60 in the valve casing and the passage 52 extending through the stem 36 and the body portion 24 of the eraser into the chamber 32. From chamber 32 the air flows through the passage 34 into the space between powder tube 10 and the stem 8, thence through the gap between the lower edge of the deflector 12 and the face of the stem 8 into the powder cup 4. As the air flows through the powder cup it picks up particles of eraser abrasive and propels them through the powder tube 10 and the jet 28, from which the air carrying abrasive issues in a fine stream.

A portion of the air admitted to the powder cup 4 will flow through the slots 14 in the cylindrical wall of the deflector 12, creating a whirlwind as indicated by air flow lines 62. The creation of a miniature whirlwind within the powder cup 4 causes eraser abrasive contained therein to be greatly agitated, producing a fine mist of eraser abrasive in the powder cup, and also increases the length of the path along which the air passes in its travel through the powder cup, thereby causing greater uniformity in the distribution of abrasive particles in the air stream which issues from the eraser.

The amount of eraser abrasive contained in the air stream issuing from the eraser may be regulated by means of the adjusting screw 16 to vary the width of the gap between the adjacent ends of the adjusting screw and the powder tube. The hardened steel inserts 18 and 20 provided at the tips of adjusting screw 16 and powder tube 10, respectively, preclude rapid wearing of these parts as a result of the severe abrasive action which takes place thereat due to the high velocity of the air stream in the narrow gap therebetween. The jet 28 is likewise subjected to severe abrasive action due to the high velocity of the air carrying abrasive issuing from the tip thereof, and therefore is preferably formed of hardened steel. It will be noted that all of the parts which are subjected to severe abrasive action are arranged so as to permit ready replacement thereof.

The jet 28 is made replaceable for the additional reason of enabling differently shaped tips to be employed-for particular types of work.

It has been found that the stream of eraser abrasive which issues from the jet of the eraser permits removal or cutting of ink, paint, or the like, from a drawing or like surface in a minimum of time without injury to the surface or adjacent areas which it is not desired to erase. To effect a complete erasure, the jet may be held close to the working surface. The eraser may also be used for highlighting or shading by holding the jet 28 some distance from the working surface, producing results heretofore unobtainable with erasers of any type.

It should now be apparent that an eraser of great utility, which is constructed in such manner as to permit delicate erasing operations to be performed in a rapid manner, has been provided.

The initial cost and the cost of maintenance of the eraser are reduced to a minimum by the provision of replaceable parts of abrasive-resisting - materials at the points where the greatest abrasive action -occurs. A high degree of uniformity in the distribution of the eraser abrasive throughout the air stream issuing from the eraser is obtained by reason of the construction of the powder cup assenbly, which requires the air to travel the full extent thereof and furthermore causes the air to traverse a spiral path during its travel through the powder cup.

While the invention has been illustrated by the disclosure of a particular embodiment thereof, it should be apparent that various modifications may be made therein without departing from the invention in its broader aspects, and therefore it is the aim in the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is: 1. An erasing tool comprising a slender hollow body portion adapted to be held like a pencil by an operator, a fitting for connecting a source of compressed air to said body portion, a finger operated valve in said body portion for controlling the flow of air therethrough, a container for eraser abrasive attached to said body portion and communicating with said valve, a jet at the tip of said body portion, and means forming a passage for directing air admitted to said container from said body portion to said jet, whereby particles of eraser abrasive are propelled through said jet by the air stream when said valve is opened during operation of the tool.

2. An erasing tool comprising a container for eraser abrasive having an inlet for compressed air and having an outlet for compressed air mixed with particles of eraser abrasive, and a cupshaped deflector having skewed openings therein disposed in alignment with the inlet in said container for causing compressed air flowing therethrough to traverse a spiral path through the container and thereby promote intimate contact between the air stream and the particles of eraser abrasive in said container during operation of the tool.

3. An erasing tool comprising a cylindrical casing having an end portion provided with an axial opening, a cover closing the other end of said casing, said cover being removable to permit eraser abrasive to be placed in the enclosure, a powder tube extending co-axially through the 65 opening in said end portion to a point adjacent said cover, the space between the other wall of said tube and the opening forming a passage through which compressed air is admitted to the enclosure, an annular deflector encompassing said tube and disposed in the path of the air stream to cause it to traverse a circuitous path through the enclosure, and a valve member extending axially through said cover and adjustably spaced from the adjacent end of said tube to regulate the quantity of eraser abrasive which is carried through the powder tube by the air stream during operation of the tool.

4. An erasing tool comprising a cylindrical casing having a cone-shaped end portion provided with an axial opening, a cover closing the other end of said casing, said cover being removable to permit eraser abrasive to be placed in the enclosure, a powder tube extending co-axially through the opening in said cone-shaped portion to a point adjacent said cover, the space between the outer wall of said tube and the opening forming a passage through which compressed air is admitted to the enclosure, a cup-shaped annular deflector encompassing said tube and disposed in the path of the air stream, said deflector having skewed openings therein to cause the air stream to traverse a spiral path through the enclosure, and a valve member extending axially through said cover and adjustably spaced from the adjacent end of said tube to regulate the quantity of eraser abrasive which is carried through the powder tube by the air stream during operation of the tool.

5. An erasing tool comprising a slender hollow body portion adapted to be grasped like a pencil by an operator, a fitting extending from said body portion for connecting a source of compressed air thereto, a finger operated valve in said body portion for controlling the flow of air therethrough, a cylindrical casing having an end portion provided with an axial opening communicating with the interior of said body portion, a cover closing the other end of said casing, said cover being removable to permit eraser abrasive to be placed in the enclosure, a powder tube extending co-axially through the opening in said cone-shaped portion to a point adjacent said cover, the space between the outer wall of said tube and the opening forming a passage through which compressed air is admitted to the enclosure from said body portion, a cup-shaped annular deflector encompassing said tube and disposed in the path of the air stream, said deflector having skewed openings therein to cause the air stream to traverse a spiral path through the enclosure, a valve member extending axially through said cover and adjustably spaced from the adjacent end of said tube to regulate the quantity of eraser abrasive which is carried through the powder tube by the air stream during operation of the tool, and a jet at the tip of said body portion communicating with said powder tube.

JENS A. PAASCHE.

REFERENCES CITED The following references are of record in the file of this patent: 25 UNITED STATES PATENTS Number 554,299 1,712,804 1,730,195 2,133,149 2,305,976 Name Date Parker ------------- Feb. 11, 1896 Wytcherly -------- May 14, 1929 Davis --------------- Oct. 1, 1929 Poncelet --------- Oct. 11, 1938 McKnight ---------Dec. 22,1942