US2840959A - Sanding device - Google Patents

Description

July 1, 1958 R. PRlTlKlN 2,840,959

SANDING DEVICE Filed June 11, 1957 /z BYOW SANDlNG DEVICE Louis R. Pritikin, Los Angeles, Calif.

Application .lune 11, 1957, Serial No. 664,984

7 Claims. (Cl. S1-187) This application is a continuation-impart of my pending Yapplication for Sanding Device, Serial No. 604,893, iiled August 20, 1956, allowed April 10, 1957, Patent Number 2,818,690, issued January 7, 1958.

This invention relates to a sanding device of the type used for sanding callo-uses and the like on the surface of the skin, although it may be used for o-ther purposes.

A general object of this invention is to provide a sanding device comprising a holder and a plurality-of strips of sandpaper stretched around said holder and secured thereby in a manner such that each strip, when worn, can be readily torn away from the holder to expo-se a fresh strip in position for use.

Another object is to provide a sandpaper holder of extremely simple and inexpensive construction which may embody simply a pair of complementary sections providing pairs of jaws at the respective ends of the holder, for clamping the ends of sandpaper strips.

Another object is to provide such a sanding device wherein the ends of the sandpaper strips will he drawn into the holder as the sections of the holder are drawn together, and wherein such drawing-in will result in placing the exposed, working areas of the sandpaper strips under tension to maintain them suiiciently Vtaut for elficient sanding operation.

Another object of the invention is to provide such a sanding device embodying means for supporting the sandpaper strips in a manner to provide a cushioning actlon in the working portions of the strips.

More specifically, the invention contemplates a sanding device embodying a recessed block. having projecting curved jaws at the respective ends thereof, around which jaws the end portions of the sandpaper strips are drawn into a recess defined between the jaws. A cap complementary to the said block, engages the ends of the sandpaper strips and clamps them in the recess. The ends of the cap, forced under compression against the inturned ends of the sandpaper strips and engaging the sand coated faces thereof, establish gripping engagement with said inturned ends to drag them into the recess of the block so as to stretch the remaining portions or" the sandpaper strips tightly around the jaws and the forward face of the block. The end portions of the jaws are reentrant, i. e., they overhang the recess in converging relation and the ends of the cap member are curved to substantially match the converging inclination of the jaws. The length of the cap is so related to the spacing between the tips of the jaws and the thickness of the interposed ends of the sandpaper strips, that interference will be developed as the cap is forced into the recess of the blo-ck, thereby forcing the jaws apart. The jaws are so related to the central web portion of the block which connects them that such web portion will be bowed away from/the working areas of the sandpaper strips to provide a cushioning action for the stretched strips. The block is of a resilient material such that the jaws, spread apart from their normal positioning, will exert yielding clamping action ice against the ends of the sandpaperstrips interposed be- `tween the jaws and the ends of the cap, whereby to maintain vthe strips securely clamped in the holder.

Other vobjects and advantages will become apparent as the ensuing specification is read with reference to the appended drawing in which:

Fig. l is a side view of a sanding device embodying the invention;

Fig. 2 is a plan view ofthe same;

Fig. 3 is a transverse sectional view thereof taken on the line 3-13 of Fig. l; and

Fig. 4 is a side view illustrating the device in the process of being assembled with :a new supply of sandpaper strips.

Referring now .to the drawing in detail, l have shown therein, as an example of one form in which my invention maybe embodied, a sanding device embodying generally a block 10, a cap 11, and a plurality of strips of sandpaper 12 which are secured between the block 11i and cap 11 as shown in Fig. 1.

Block 10, in longitudinal section, is of shallow U-form, comprising a pair of jaws 13 as the end portions thereof and an intermediate web 14 integrally joining the jaws 13. Defined between the web 14 and jaws 13 is a recess 15 in which the cap 11 is received with the ends 1?. of the sandpaper strips 12 interposed between the jaws 13 and the ends of the cap 11 at 16. Strips 12 are stretched under tension around -block 10.

Jaws 13, in side elevation, are generally crescentshaped, having a maximum width considerably greater than the thickness of web 14 and having tip portions 16 overhanging the recess 15, the inner yfaces of tip portions 16 converging toward the gap 17 which is defined between the extremities thereof. silient, elastic material.

As a suitable elastic material for the block 1t? and cap 11 the invention may utilize unplasticized synthetic resin .thermoplastic material (such as methyl-methacrylate) resistant to cold iiowing and loss of elasticity, and, owing to the greater thickness of the jaws 13 than the web 14, and the fact that the cap 11 has va length greater than the gap 1'7 (as reduced by the thickness .of strip ends 12 interposed between the ends of the cap and the jaw tips 16) the block will be deformed from its unstressed conguration shown in Fig. 4 to the bowed condition shown in Fig. l as the result of the spreading jaws 13 which, as they tilt away l from one another at their tips 16 will force the web 14 to bow toward the cap 11 as shown in Fig. l, thus separating the web 14 from the working portions 18 of the sandpaper strips stretched between the heel portions 19 of jaws 13, so that the working portions 18 of the strips will have a cushioning action as they are lightly pressed against a surface being sanded.

The ends of cap 11 have cylindrically curved convex end faces 20 corresponding generally to the cylindrical concave curvature of the inner walls of jaws 13, whereby the convex ends of cap 11 will `be pocketed in the concave recesses defined by the inner walls of jaws 13. The terminal portions of concave faces 2,0 where they intersect the flat outer faces of cap 11, are converged toward said outer face to correspond generally to the converging inclination of the inner faces of jaw tips 16, whereby the cap 11, when once inserted completely into recess 15, will be securely retained therein by the wedging action of the converging tips 16 spring-pressed thereagainst. The exertion of considerable force is required to remove the cap 11, once fully inserted, and thus there is no likelihood of the cap working out of the recess 1S. Conversely, the bottom of cap 11 engages the inwardly bowed Vcentral area of web 14- to prevent the cap becoming displaced any deeper in the recess. This is important be- The block 1l) is of .a recause such inward displacement would tend to relax the grip of the ends of cap 11 against the sandpaper end portions 12.

The central working portions 18 of sandpaper strips 12 are stretched under tension between the jaws 13, the intermediate end portions of the strips are stretched around the convex end faces of jaws 13, and the end portions 12 of the sandpaper strips are clamped tightly between the end faces of cap 11 and the jaw tips 16 with the latter spring loaded inwardly by the elastic forces in the bowed web portion 14 of the block. These elastic forces may be supplemented by firm bearing engagement of the bottom of cap 11 against the center of bowed web 14, with the cap 11 in turn being securely held in this position by the overhanging jaw tips 16. The net result may be a fairly high tension loading of the working portions 18 of the sandpaper strips.

To set up this tensioning of the strips, the parts are assembled as indicated in Fig. 4. The ends of the strips at one end are bent around the sharp edge of one of the jaw tips 16 and the corresponding end of the cap 11 is fulcrumed against these inturned ends, as shown at the right end of Fig. 4. The sandpaper strips are then drawn as tightly as they can be stretched by the fingers, and the opposite ends thereof are bent inwardly around the ends of the other jaw tip 16, as shown in Fig. 4. The mating end of cap 11 is then placed against these inturned ends of the sandpaper strips, and pressure is applied to the outer face of the cap 11 adjacent this end portion which has not yet been inserted into the recess. This application of pressure results in high compressive engagement of the end of cap 11 against the inturned end of the sandpaper strip. Because of the roughness of the sanded surfaces, the end of the cap will securely grip the end of outermost sandpaper strip, and as the end of the cap is pushed into the recess 15, the entrained ends of the sandpaper strips will be dragged around the jaw tips 16 and into the recess, tending to highly stretch the sandpaper strips. At the same time, the jaw tips 16 will be spread apart, with an opposite tendency to relax the tension of the sandpaper strips. The amount of shifting movement of the sandpaper strip ends around the jaws 16 however is sulhcient to more than offset the relaxing tension developed by the spreading of the jaws, and the net result will be the development of a fairly high tension load in the sandpaper strips at the end of the insertion operation, which is determined by bottoming of the cap 11 against the web 14 as the latter isv bowed inwardly. If there is not'sufcient slack in the sandpaper strip to completely follow the end of the cap 11 in its movement into the recess, some slippage between the end of the cap and the sandpaper strip will occur in order to allow the cap to complete its movement into the recess.

In the insertion of cap 11, the one end will have a pivotal fulcruming action in the recess of the adjoining jaw 13 while the other end of the cap exerts a camming action against the tip of the other jaw, to effect the spreading of the two jaws. The concave curvature of the end face of such other end s effective in establishing this camming action.

The jaws 13 have semi-cylindrical end faces 22 which are tangent to the underface of bottom web portion 14 of the block, to facilitate the sliding movement of the `sandpaper strips around the ends of the block during the assembling operation.

The cap 11 has in its respective sides, longitudinally extending depressions 23 to receive the tips of the fingers and the thumb of the operators hands, thus facilitating the grasping of the cap which functions as a handle in the use of the device.

When a strip of sandpaper has been worn down by use, it may be removed to expose a fresh sanding surface therebeneath. This is done by using a knife or a pair of scissors to sever the stretched central portion of the outermost strip, the point of the blade being inserted between the outermost strip and the next strip. The severed ends of the strip are then peeled away from the underlying strip and are torn off where the strips bend inwardly around the sharp edges of jaw tips 16. vThese sharp edges may be utilized as tearing edges against which to sever the separated strip portions from the holder.

What is claimed is:

1. In a miniature sanding device for cosmetic use, in combination: a plurality of superimposed sandpaper strips; and a holder in which the ends of said strips are clamped, with the strips stretched around the holder, said holder comprising: a block which in longitudinal section is of shallow U-form, defining an elongated depression, said block including a bottom web and a pair of jaws projecting upwardly from the respective ends thereof, said jaws defining concave inner faces which are slightly converging upwardly at the tips of said jaws to define a restricted pass, and a cap member having a longitudinal cross sectional contour corresponding generally to that of said depression, received in said depression and having rounded ends mating with said concave inner jaw faces, the tip portions of said strips being clamped between said jaws and said cap ends with said jaws sprung apart, and with said bottom web consequently bowed upwardly, and with said strips stretched between said jaws in spaced relation to the bowed lower face of said web to provide a cushioning action in the use of the device, said bowed web functioning to spring-load said jaws into clamping engagement with said strip ends, the converging end portions of said jaw tips overhanging said cap ends and thereby securing the cap in said depression.

2. A sanding device as dened in claim l, wherein said jaws, in side elevation, are of crescent shape, with substantially semi-cylindrical end faces tangent to the underface of said bottom web portion of the block to facilitate the sliding movement of said sandpaper strips around the ends of the block while under tension, in the assembling of the device. i 3. A sanding device as defined in claim 2, wherein said upwardly bowed bottom web engages the bottom of said cap to maintain the ends of the cap pressed upwardly against the strip ends as seated against said overhanging end portions of said jaw tips.

4. A sanding device as defined in claim l, wherein said cap member has longitudinally extending depressions in its respective side faces, to receive the finger tips and facilitate the grasping of the cap as a handle for the device.

5. In a miniature sanding device for cosmetic use, utilizing a plurality of superimposed sandpaper strips: a

Vholder comprising a block which in longitudinal section is of shallow U-form, defining an elongated depression, said block including a bottom web and a pair of jaws projecting upwardly from the respective ends thereof, said jaws defining concave inner faces which are slightly converging upwardly at the tips of said jaws to defne a restricted pass, and a cap having a longitudinal cross sectional contour corresponding generally to that of said depression, received in said depression with aggregate clearance between the ends of said cap and said jaw tips slightly less than the aggregate thickness `of said strips, whereby the ends of said strips, when inserted between sai-d jaws and the ends of said cap, will spring said jaws apart, said block being of hard, elastic material having a loading capacity such yas to clamp said strip ends tightly between said jaws and said cap ends, said cap having rounded end faces adapted to establish secure frictional engagement with the sand coated faces of said strip ends, one end of said cap being adapted to pivotally fulcrum against the concave face of one jaw and the other end of said cap being adapted to exert a camming action against the tip of the other jaw when subjected to pressure forcing the cap and interposed strip ends into said depression, whereby to spread said jaws and permit the cap to enter said depression through said restricted pass, said rounded ends of the cap becoming locked between said conc-ave inner facesV of the jaws to securely mount the sandpaper strips to said block member, said bottom web being of less thickness than said jaws, whereby the springing of said jaws apart by the interposed cap and strip ends will cause said bottom web to bow upwardly to provide a cushioning air space between said bottom web and the central portions of said strips stretched between the ends of said block member.

6. A sanding device as defined in claim 5, wherein the engagement of said other end `of the block against the interposed strip ends in exerting said camming action against the opposed jaw tips, will cause said interposed strip ends to be securely gripped by said other end of the cap and dragged into the recess so as to place said sandpaper strips under tension between the ends of the block.

7. A sanding device as defined in claim 6, wherein the thickness of said cap is so related to the depth of said recess that the bottom of the cap will engage the inwardly 6 bowed central area of said bottom web of the block when the ends of said cap are mated with said concave inner faces of said jaws, whereby to limit the inward movement of the cap into the recess and thereby maintain suicient spreading of the jaws when the cap is fully received in the recess.

References Cited in the file of this patent UNITED STATES PATENTS 1,737,135 Windfeldt Nov. 26, 1929 1,910,647 Steeg et al. May 23, 1933 2,040,599 Davies May 15, 1936 2,464,385 Eisele Mar. 15, 1949 2,657,508 Schubert Nov. 3, 1953 FOREIGN PATENTS 350,391 Germany Nov. 21, 1920 438,824 France May 29, 1912

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