US2330208A - Method and apparatus for belt surfacing - Google Patents

Description

H. B. FAY 2,330,208 METHOD Am) APPARATUSHFQR BELT sunFA difie Sept. 28, 1943.

2 Sheets-Sheet i -fltaliih e of INVENTOR. HORACE. B. FAY

ATTORNEYS.

H. B. FAY gamma METHOD AND APPARATUS FOR BELT SURFAGING Filed Nov. 8, 1939 2 Sheets-Sheet 2 INVHHUR HQWAQ'E B. Fm

ATTORNEYEY/ Patented Sept. 28, 1943 METHOD AND APPARATUS FOR BELT SURFACIN G Horace B. Fay, Willoughby, Ohio, assignor to The Stratmore Company, Cleveland, Ohio, a corporation of Delaware Application November 8,1939, Serial No. 303,418

2 Claims. (01. 51 17o) The present invention relates, as indicated, to an improvement in methods of surfacing and more particularly to an improved method of conditioning surfaces such as pressed metal body panels of motor cars, and other articles having a surface which must be cut down to a smooth and generally level condition.

The principal object of my invention is to provide a, method for rapid, economical and emcient conditioning of such surfaces to remove slight projections, welding seams, and the like, so that the surface may be properly prepared for the reception of paint or other finish to be applied thereto. The same method, and apparatus therefor, may be employed to rub or prepare the surface between intermediate or finishing coats.

For proper preliminary preparation of such types of metal and other surfaces as are to receive a highly polished finish, it is of utmost importance to prevent breakage of the abrading or rubbing member. This abrasive element, such as the abrading belt in a surfacing machine, travels, of course, at high speed, approximating 5000 feet per minute. Breaks, rents or cracks in the abrasive means usually cause digging or other damage to parts of the surface which necessitates further work thereon. In addition, when a belt is thus injured, it must be replaced, and full efficiency, i. e. use up to a point where the abrasive is worn out, is substantially reduced. To eliminate these difficulties, I .have provided a method whereby uniform and efiicient surfacing is effected, together with longer life and lower cost in the abrading material employed.

In the present invention, I have provided a tool having means for driving an abrasive belt at high speeds and one which the operator can easily handle and use against the surface to be finished or rubbed. I prefer to employ an abrasive belt, made preferably of a strip of vulcanized fibre or chemically treated paper stock, with sufficient flexibility to travel around pulleys set within the frame of the surfacing tool, but relatively stiff and resistant to tensile strains, thereby forming a satisfactory support for the abrasive grains which are bonded thereto. Cloth belts have, of course, a soft yielding surface, whereas a treated paper stock belt is relatively non-indentable and does not yield.

The strength and durability of such a belt as suggested depends to a large extent upon the moisture content of the fibre or paper stock. If the moisture content of the belt in operation drops below a required predetermined amount, herein called the low moisture percentage limit,

' point of brittleness where it is easily ruptured or cracked by sudden strains, etc. Vulcanized fibre or a substantially equivalent material of overbeaten paper stock are moisture absorbent in nature and such a belt has its unusual strength only when its moisture content is properly maintained. If the belt is permitted to dry out in operation, tensile strength-and resistance to shocks are rapidly reduced.

To prevent such drying and to maintain the abrasive belt at its most efficient moisture content, have mounted moistening means on the frame of the machine to supply a predetermined amount of moisture continuously to the inside or non-abrasive side of the belt, the moisture so supplied being controlled to maintain the belt at its most efficient operating point between its high and low moisture. percentage limits.

The frictional heat engendered in the rubbing or abrasive action of the belt tends to soften the glue or bond in which the abrasive grains are set, thus permitting the grains to roll into a position where least frictional resistance is provided. Surfacing efficiency is thereby reduced. By use of the moistening means mentioned above, I have provided a way to reduce the temperature of the abrasive belt to the point of efliciency at which the glue holds the abrasive grains in their effective position for cutting. Spraying with moist air tends to cool the belt and maintain the bond at a temperature point below that at which it softens.

The moving action and speed of the belt tends to increase the rate of evaporation, thus further resulting in additional temperature control as a corollary to the provision for moisture application to the belt.

Another advantage in my improved method of belt surfacing and apparatus therefor, is the provision for a yielding supporting means for the abrading belt at that portion of it in contact with the treated surface. As explained above, when a portion of the surface of the abrading belt encounters projections, weld seams and the like, such portion is subjected to sudden uneven strains. To carry the belt over these projections without breaking or cracking, and to condition the treated surface uniformly without gouging, etc., a yielding, supporting means is provided for the surfacing belt which furnishes stifi transverse support plus shock-absorbing action for longitudinal strains, as will hereinafter be described.

These aforementioned steps make up the essentials of my improved method of surfacing.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims; the annexed drawings and the following description setting forth in detail certain means of carrying out the invention, such disclosed means and mode illustrating, however, but two of various ways in which the principle of the invention may be used.

In said annexed drawings:

Fig. l is a vertical transverse section through the apparatus in my invention;

Fig. 2 is a side view of the apparatus of Fig. 1 showing schematically the moisture system;

Fig. 3 is a section similar to Fig. 1 showing a modification of the moisture supplying mechanism; and

' Fig. 4 we perspective of the supporting belt.

My drawings illustrate an improved form of rubbing or surfacing machine of the general type shown in U. S. Patent No. 1,487,398, issued to R. A. Moore on March 18, 1924. Referring particularly to my Fig. 1, there is shown a suitable casing or frame I6 in which is housed a motor I8 here shown as being of the fluid pressure type, but which, of course, may be of any suitable type and which need not be described in detail. Mounted in the frame is a series of pulleys or rollers III and II, there being a plurality of rollers II preferably arranged in the same plane and serving as a support for an abrasive or rubbing belt I2 which passes over all the pulleys. The pulley I0 is preferably knurled or roughened to engage with and drive the belt I2. If desirable, positive drive means may be employed instead of the frictional drive described. The pulley I0 ismounted on a shaft I3 having a gear I4 driven by a pinion I5 carried by a second shaft H which is driven from the motor shaft by gears I9 and 20. An idler pulley 2| is mounted on the interior of the casing and serves to maintain the proper tension on the belt l2.

Mounted within the belt I2, is a second belt 22, preferably formed of material which has a limited longitudinal and lateral stretch so it can act as a shock absorbing device for the abrasive belt which it supports against the work. This belt passes over and around only the pulleys II and merely serves as a support and backing for the belt I2 over the working (rubbing or abrading) area.

The pulleys I0 and II are mounted on a suitable framework 20 which is provided on either side with guides to prevent sidewise displacement of the moving belt. The bottom of the casing I6 is open and the frame 20, with the pulleys and belts, may be inserted in such open end and locked therein by suitable keys or latches. The position of these latches determines the inner position of the framework 20, and this position will be such that, as the framework is moved into the casing the belt I2 engages against the idler pulley 2| and is tensioned only when inserted in the casing in operative position. When the framework and belts are removed from the casing, the belt is relatively loose and may readily be removed for replacement or repair.

Mounted on the framework 20 is shown means for moistening the inner surface of the belt I2, such means being shown as consisting of a spray gun or nozzle 30 so spaced from the belt as to spray the same evenly as it travels past the nozzle. Moist air is preferably employed, the air being supplied from the air line for the fluid pressure motor, if used, or from any suitable air line 3|, and being passed through a suitable humidifying chamber 32 to charge it with the requisite moisture content. The air gathers moisture in this chamber from which the moistened air is passed through a conduit 33 provided with a valve 33a to a conduit 34 which leads to the nozzle 30. If more moisture is desired, a valve 3411 may be manipulated for permitting water or the like to flow through a conduit 34b directly from the chamber 32 to the conduit 34.

Other types of moistening means may be employed such as the spray gun 35 shown in Fig. 3, which is of the usual two line type, one, 36, supplying air and the other 31, water or moistening fluid and being controlled to provide the required amount to the back of the belt. It is, of course, understood that any suitable means for evenly distributing moisture may be used provided that. control thereof is obtainable.

The operation of the device will be readily apparent from the foregoing description. The operator grasps the device by the handle 43 and moves it over the surface of the work to be treated.

To obtain the desired shock absorbing action in the supporting belt, as shown in Fig. 4, it is preferably formed of a relatively thick layer 40 of woven material which will stretch both longitudinally and transversely. This is preferably coated with a thin layer M of rubber or other waterproof material so as to prevent deterioration from being constantly moistened by the abrading belt.

In the present device, use is preferably made of a belt I2 of treated paper stock, which may be either of two types, true vulcanized fibre, or pseudo-vulcanized fibre. In true chemical vulcanizing the fibers of paper pulp are gelatinized and bonded together during manufacture. In the pseudo-vulcanized fibre, raw paper pulp is overbeaten in water without chemical additions. It will be understood that when I speak of a belt of chemically treated paper stock both of these materials are included.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the product and method herein disclosed, provided the step or steps stated by any of the following claims or the equivalent of such stated step or steps be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a method of surfacing by means of a continuous belt passing over guides and comprising backing material having abrasive adhesively secured to the backing material, the backing material having a tendency to dry out and become brittle during use in the atmosphere. the step of directing a gaseous stream against the abrasive opposite side of said backing material, the moisture content of the stream being such that it prevents the backing material from said'guides in raw atmosphere, means for driving said belt at a, high speed, and means for directing a stream of artificially moisture treated air against said backing whereby said belt can be continuously used longer than it could in the absence of said stream.

- HORACE B. FAY.

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