US2028874A - Sanding device - Google Patents

Description

Jan. 28, 1936. p KRAMER E AL 2,028,874 I SANDING DEVICE Filed uarch 16, 1934 INVENTORS.

ATTORNEYS.

l mented Jan. 28, 1936 UNHTQEQ aceasvi sannnvc nsvrcn Application March 18, 1934, Serial No. 715,797 ill Claims. (Ci. 51-195) This invention relatesto devices for sanding surfaces of various coats of finishing material applied to objects such as automobile bodies, and more especially to disks sor pads employed in ,5 such devices. i

The principal object of the invention is to incprove the art of smoothing and finishing the surface of an object.

Another object is to provide a power device of 1c the above character which effectively smooths the surface of a finishing material by cutting down such material to the level of the depressions therein rather than merely grinding or eroding the material by cutting down the low spots or in depression as well as the high spots.

a further object is to prevent excessive rolling of a mobile abrasive composition and rendering the latter relatively fixed with respect to the working surface of a sanding device to effect a shearing so action in addition to an eroding or grinding action.

It is a further object to provide a power device for cutting down the so-called jorange peel surface in lacquer or under coats without mate rially scratching the same.

Other objects, features and advantages will,

become apparent from the following description and appended claims. v

In finishing the surface oi an object such as oil a metallic body of an automobile or the like, it is customary to clean the object so that finishing materials will more or less permanently adhere thereto and then apply primer and surfacer coats, or primer-surfacer coats, a combination of the 35 above coats, which coats are used to fill surface defects in the obi ct as well as to improve the adhesion of finishing coats of material such as enamel or lacquer to the object to be finished. The undercoats do-not dry with a smooth, plan ular surface but rather present a rough appearance and some orange peel effects common to the majority of lacquers. It is necessary to cut down the surfaces of such materials to a plane substantially at the level with the base of the eepest depressions therein. It has been the usual practice to cut down the surfacer coat with sand paper by manual operation. To reduce the labor involved it'is desirable to employ a mechanical device wherever possible. The mechanical. devices which have been introduced to accomplish this cutting operation have been either of the rotating wheel or reciprocating type, both employ ing water or other liquid as a cooling and lubricating medium. The reciprocal type of device 55 usually includes two flat members each covered with a strip of sand paper and reclprocated by compressed air to simulate the effect of manually sanding. In this type of device a sander light enough to be easily handled has too short a. stroke to effect good results, and in devices where the 5 stroke has been lengthened, the device becomes heavy, unwieldy, noisy, and not easily adapted to curved or irregular surfaces. The power driven rotating wheel type of sanding device is consid erably lighter and more flexible in operation. The latter devices normally employ a disk of sand paper, backed by a disk of sponge rubber, or similar material, or employ fixed abrasive disks which consists of a mixture of rubber or other binder and 90 per cent or more of abrasive, or multiple layers of fabric on which are imposed layers of abrasive and binder. The majority of these disks v are hard and flexible.

None of the above power devices is adapted for use on any but fiat surfaces, so that in sanding an object such as an automobile body but approximately 50 per cent of the surface may be smoothed by such devices and the remainder must be done manually. In sanding certain types of under coats, these devices have been employed with some degree of success on fiat surfaces only. Care must be taken, however, asthese devices easily gouge the surface if incorrectly applied thereto or if allowed to strike a protuberant part such as a hinge, or the like, a nick is produced in such part, and it sand paper is used as the cutting disk, the latter is torn and must be replaced.

Other attempts have been made to finish under coats by employing the rotating wheel type of 5 sander in conjunction with various types of pads and a mobile abrasive composition. While this device has been employed with a considerable degree of success on finish coats, none of the pads has proved successful on under coats for any considerable length of time. Too soft a pad fails to cut down the orange peel due to rolling of the abrasive with respect to'the surface of the pad, and too hard a pad will not cut down the orange peel surface without producing too deep scratches. Pads of the proper degree of hard ness while cutting fairly well at the start wear out too quickly to prove practical. For pads of this type various materials such as felt, leather, rubber, sponge rubber with various covers, carpeting, canvas belting, steel wool, sheep skin, have been tried.

The present invention contemplates the provision of a pad adapted to be employed on a'rotating wheel and in conjunction with a mobile abrasive composition, the pad being of such composition and design that a shearing action is produced in addition to an eroding or grinding action so that orange peel effects may be removed without excessively scratching or gouging the surfaces treated. The device is also applicable to curved as well as fiat surfaces.

For the purpose of illustrating the genus 'of the invention, a. typical concrete embodiment thereof is shown in the accompanying drawing, in which:

Figure 1 is a cross-section of a finishing or polishing tool or head employing a sanding pad constructed in accordance with the principles of this invention;

Fig. 2 is an enlarged front elevation of the sanding pad shown in Fig. 1;

Fig. 3 is a section taken on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged section taken on the line 4-4 of Fig. 2; and

Fig. 5 is a front elevation of a modified form of sanding pad. v

Referring particularly to Fig. l of the drawing, an automobile body portion H! has disposed thereon a suitable coating of surfacing material II, which when dried presents surface irregularities which must be cut down in order to present a smooth or planular surface. In order to remove such irregularities, the surface of the coating material H is covered with a suitable water base or oil base abrasive composition and the latter moved at high speed along the surface under the influence of a suitable power device to shear 1 face of coating material II by a rotating head 12 of a polishing or finishing tool l3. This tool may be driven directly, by any suitable source of power as, for example, an electric motor, or may be driven by a flexible shaft M extending from a remote source of power through flexible conduit l5 and having its end threaded as indicated at 16 into a flanged sleeve I! by which the head 12 is rotated. The end of the flexible conduit l5 adjacent the head l2 extends into and is rigidly secured to a tubular member I8 by which the head may be held manually in any desired position during operation of the device.

The head 12 comprises a relatively fixed, although flexible disk 20 secured to the flanged end 2| of the sleeve H by rivets 22 and a larger concentric flexible disk 23 which is secured removably to the head by a relatively flat headed stud bolt- 24 projecting through axial openings in the disk and therebeyond in a centrally disposed opening in the end of the sleeve l1.

Reference may now be had to Figs. 2, 3, and 4 in which the disk 23 is shown as having radially disposed corrugations 25 spaced by similarly disposed depressions 26 extending from the central portion of the disk to a point spaced from the peripheral margin thereof The corrugations and depressions are thus both arranged perpendicular to the line of motion of various parts of the working face of the disk 23. This disk is preferably constructed of a medium hard felt, or similar material, and the depressions are formed by placing the disk in a suitable press. After corrugating the working surface of the disk this face is treated with one or more coats of lacquer, primer or similar waterproofing and binding medium 30 to render the working surface hard and nonabsorbent. This renders the form of the working face of the disk durable and of permanent form.

The peripheral edge 3| of the disk 23 is beveled to remove any corners of the felt to prevent gouging or other injuries to the surface H to be treated.

As will be indicated in Fig. 4 of the drawing, the top surfaces of the corrugation 25 are of slightly rounded contour and the working surface of the disk as impregnated by the lacquer or binding coating 30 is still rough enough to carry the abrasive composition along the coating material during rotation of the head [2. This causes the abrasive composition to shear off projections or high spots of the surface of the coating material H Without materially grinding or eroding such surface by rolling the abrading composition between the disk 23 and the-coating material ll. disk 23 is sufiiciently .yieldable so that objectionablydeep scratches are not produced. Such scratches are produced may be a y removed by polishing with a sheep skin or lamb skin pad or disk. The impregnating coating 30 renders thezgw'orking surface offlthe disk follow the depressionswithinthe surface of the coating material I I and do not cause the abrasive composition to be rolled therethrough so as to wear away the depressions as well as the highspots. The provisionof depressions 26 between the corrugations 25 interrupts any rolling action of the abrasive composition so that but a slight amount of grinding or eroding of the surface of the coating material ll results. The head l2 of the polishing or finishing tool is preferably rotated at a speed of from 850 to 1100 revolutions per minute. While the working surface of the disk 23 is hardened by the impregnating composition 36, it is noted that the flexibility of the disk is not materially changed. so that in conjunction with the relatively thick flexible backing disk 20 the sanding device may be employed for polishing curved as well as flat surfaces as indicated in Fig. 1.

Referencemay now be had to Fig. 5 of the drawing in which a modified form of sanding pad 33 is shown. This pad is also composed of a medium hard felt, or similar material, and has corrugations 35 spaced by curved depressions 35 extending generally in a substantially radial direction from the central portion of the pad to points spaced trom the periphery of the pad. This pad is adapted to be rotated in the direction indicated by the arrow, counterclockwise as viewed in Fig. 5. A surfacing and hardening coating of lacquer, primer or other waterproofing and. binding material is applied to the work ing surface as in the previous embodiment. The depressions 36 in the outer or peripheral portion of the pad extend or curve somewhat toward the direction of rotation so as to carry an abrasive composition along the working surface and partially prevent the abrasive from being thrown centrifugally from the periphery of the pad. The functions of the corrugations and depressions are otherwise the same as in the previously described embodiments.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be effected without departing from the spirit thereof, it is intended that all matter containedin the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

sufficiently hard so that. parts thereof do not.

What is claimed is:

1. A sanding device adapted to be employed in conjunction with a mobile abrasive composition and comprising a pad composed of an inert material, means for moving said pad in a predetermined direction, said pad being provided with spaced depressions pressed into its working surface and extending in a direction substantially normal to the direction of motion of said pad, and a binding material, impregnating the working surface of the pad to maintain the form thereof.

2. A sanding device adapted to be employed in conjunction with a mobile abrasive composition and comprising a pad composed of a medium hard felt, means for moving said pad in a predetermined direction, corrugations formed on the working surface of said pad with the depressions thereof extending in a direction normal to the direction of movement of said pad, and a coating material impregnating the working surface for hardening and maintaining such surface in corrugated form.

3. A sanding device adapted to be employed in conjunction with a mobile abrasive composition and comprising a disk-like pad, and means for rotating said pad, said pad being provided with corrugations on its working surface and arranged substantially radially of said disk-like pad, said corrugations terminating inwardly of the periphery of said pad.

4. A sanding device adapted to be employed in conjunction with a mobile abrasive composition and comprising a disk-like medium hard felt pad and means for rotating said pad, said pad being provided with substantially radially disposed depressions pressed into its working surface and terminating short of the periphery of said pad.

5. A sanding device adapted to be employed in conjunction with a mobile abrasive composition and comprising a disk-like pad, means for rotating said pad, said pad being provided with spaced depressions pressed into its working surface and extending in radial directions with respect to the axis of rotation of said pad, and a binding and waterproofing material impregnating the working surface of said pad to increase the permanence of the form of said working surface.

6. A sanding device adapted to be employed in conjunction with a mobile abrasive composition and comprising a pad composed of a disk-like medium hard felt, means for rotating said pad, said pad being provided with spaced depressions pressed into its working surface and extending in substantially radial directions with respect to the axis of rotation of said pad, and a coating material impregnating the working surface of said pad for increasing the permanence of form of said working surface.

7. A sanding device adapted to be employed in conjunction with a mobile abrasive composition and comprising a pad composed of a disk-like medium hard felt, means for rotating said pad, corrugations formed on the working surface of said pad with the depressions thereof extending in radial directions with respect to the axis of rotation of said pad, and a coating material impregnating the working surface of said pad for hardening and maintaining such surface in corrugated form.

8. A tool adapted for use in conjunction with a mobile abrasive composition for removing surface irregularities from an applied coating material comprising a disk composed of a medium hard felt and having sufficient flexibility to follow the general surface contour of said coating material, said disk being provided with spaced and radially disposed corrugations on the working surface thereof, a hardening material impregnating the working surface of said disk for preventing the latter from following the surface irregularities in the applied coating material, a flexible and rotatable backing disk, and means for securing said first disk on one surface of said backing disk for rotating the felt disk.

9. A tool adapted for use in conjunction with a mobile abrasive composition for removing surface irregularities from an applied coating material comprising a driven shaft, a reinforcing disk of relatively thick but flexible and resilient material secured to the shaft and having a substantial marginal portion free for resilient flexing, a disk composed of a medium hard felt arranged on the exposed surface of said reinforcing disk and having a substantial marginal portion projecting beyond the marginal edge of the reinforcing disk, the working surface of said felt disk being provided with spaced depressions pressed therein and arranged in generally radial relation with respect to the axis of rotation of said disk, and a hardening material impregnating the working surface of said felt disk for increasing the permanence of form of said workingsurface.

10. A sanding device adapted to be employed in conjunction with a mobile abrasive and comprising a disk-like pad, means for rotating the pad in one direction, said pad being provided with corrugations on its working surface arranged in a generally radial direction and having the portions thereof adjacent the periphery of the pad inclined toward the direction of rotation of the pad.

11. A sanding device adapted to be employed in conjunction with a mobile abrasive and comprising a disk-like medium hard felt pad and means for rotating said pad in one direction, said pad being provided with curved depressions pressed into its working face and extending in generally radial directions with the portions thereof adjacent the periphery of the pad curved toward the direction of rotation of the pad.

PAUL H. KRAMER. JESSE C. THOMPSON.

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