US376786A - David scbymgeoue - Google Patents

Description

(No Model) L 1). SORYMGEOUR. FRAME FOR SCHOOL SLATES.

N0. 376,786. Patenjed 8811.24, 1888.

\M'kHEEEEE U ITED STATES PA E T OFFICE."

DAVID SORYMGEOUR, or Morison, MAINE, Assicnoa TO THE PARAGON NOISELESS soHooL SLATE COMPANY, or SAME PLACE.

FRAMEFORSCHOOL-SLATES.

SPECIFICATION forming part of Lettes Patent No. 376,786, dated January 24, 1888.

7 Application filed Jnre 4. 1887. Serial No. 240,252, (X model.) i

To all whom it may concern:

Be 1t known that 1, DAVID SORYMGEOUR, of M onson, 1n the county of Piscataquis and State of Maine, have invented certain new and use-- ful Improvements'in Frames forSchool-Slates; and I do hereby declare that the'following is a full, clear, and exact description of the same, referencebeing had to the ac'companyingdrawngs, forming a part of this specification, and

IC 1n which- 7 Figure 1 represents an isometric view of a school-slateembodyingmyimprovements. Fig. 2 1s a cross or transverse section thereof, upon an enlarged scale, taken on line a a, Fig. 1, r 5 wlth the central porti'onofthe slate and frame broken away. Fig. 3 represents part of a thin, fiat, metallic strip, such as is used in the construction of my improvedslate-frame. Fig. 4 representssaid strip after having been cut into thedesired shape to form one of the corners of the frame, hereinafter more fullydescribed; and Figs. 5 and 6 represent a side and edge v ew, respectively, of one of the corners ofthe frame made from a cut strip, such as'shown in Fig. 4, after having been bent into the proper form and prior to being covered with rubber, as will also be hereinafter explained.

The object of my invention is to produce a school-slate frame, which shall be noiseless as well as elastic, so that it may not be easily v broken when dropped upon any hard substance, and that will not readily slide upon or scratch any smooth surface upon which it may be placed when in use.

Said invention relates more especially to improvements upon the slate-frame for which Letters Patent of the United Stateslwere granted me May 8, 1883, and numbered 277,16l.

My 1nvention consists in combining'with the 4o edges of an ordinary slate a hollow frame I madepreferably of thin sheet metal, cut and bent in a peculiar manner to produce circular outer and square inner corners having smooth unwrinkled surfaces, and covered with'rubber vulcanized and molded into the desired shape, as hereinafter more fully set forth.

To enable others skilled in the art to which my invention. appertains to better understand the nature and purpose thereof, I, will now proceed to describe it more in'detail.

' Referring to the drawings, the part marked 7 1) represents an ordinary school-slate,andc

my improved frame, which is constructed and applied to the edges of said slate in the follow Theframe 0 comprises an inner 55,

ing manner. supportingandstiffeninghollowcasing,d,made preferably ofthin sheet metal,'and coated upon the exterior with vulcanized rubber e, as before stated. i

In making the casings d, the sheet metal is 63 first cut into strips similar to the piece'f, shown in Fig. 3, and of the proper widths and lengths to form the desired sizes and widths of frames. Said strips are then cut, by means of suitables dies, into substantially the shape 65 shown in Fig. 4, and atthe proper places to produce the corners, each corner, it will'be understood, being cut as shown in said Fig. 4. J The strips having been thus cut-,are now bent in any suitable manner into the shapes shown in" Figs. 2, 5, and 6, ready to be applied to the edges of the slates. r Bycuttingand bending the strips inthe manner shown it will be'observed that the straight edges 9 form the miter-joints g. The v curved edges h, the rounded corners h ,.and

the central narrow connecting-strips, i, which extend around the corners aforesaid, serve to hold the parts j of the metallic casing together and to protect the corners of the slate when 86 ing of rubber, which is applied in the follow- 90 I ing manner, and substantially as described-in my formerpatent previously cited. The rnbher in an unvulcanized state is first fitted over' the casing, the same being extended nnder'the inner edges, k k, thereof, next to the slate, as 5 shown inFig. 2. Itis then subjected topressinc and heat .whilein contact with sulphur by I I means of a pair of molds, one upon each side of the frame, whose outer contour corresponds to the shape desired to be imparted to said ICO' frame. V This process causes therubber to be vulcanized or hardened, so that itwill retain permanently the shape imparted to it, and also to adhere with great tenacity to the surface of the metal casing, as well as to the edges of the slate, thereby effectually preventing dirt and other foul and filthy matter from entering under the edges of the frame when in use, which obviates a serious objection in many of the old slates, and notably those having wooden frames. Being thus constructed,it may therefore be easily kept clean and free fromallimpurities, and the frame being both strong and elastic greatly reduces the liability to breakage of the slate, as well as rendering it as nearly noiseless as is possible.

Another advantage which the frame possesses over the usual wooden frames is that it retains its position wherever placed without slipping, consequently not requiring to be held while in use. By thus adhering to the surface upon which it is placed the slate is not liable to be pushed off upon the floor and broken.

The casing d, although made of light stock, is strong and not easily bent, owing to the ribs d d, formed longitudinally thereon, as shown in Fig. 2; and, if desired, additional strength may be imparted thereto by making the same with two or more ribs or corrugations, instead of as shown. Said ribs constitute one of the important features of my invention, as I am enabled to obtain the requisite strength with lighter stock, and thereby reduce the cost of the frames. I do not, however, limit myself to said construction, as it does not constitute an essential feature of said invention; but I do limit myself to the manner of forming the corners of the frame, substantially as shown and described, and to the method of applying the outer rubber coating 7 to said frame, as previously specified, and

pointed out in the claims.

I thus limit my invention in view of the United States Patent No. 360,327, granted to Peter G. Ritchie, for improvements in school- By the employment of a sheet-metal casing,

as described and shown in my present application, instead of a wire,as in my former patent, I am enabled to obtain the desired shape of frame with a largesaving in rubber, while at the same time producing a much stronger frame.

What I claim is 1. A frame for school-slates, consisting of an inner supporting-case made from a strip of sheet metal or equivalent material of proper width and length, out to form the corners,w1th mitered sides, rounded edges, and the narrow connecting-strip over each corner, then bent and fastened over the edges of the slate, and an outer coating of rubber or similar elastic material enveloping said case and extending under the edges thereof,substantiall y as shown and specified. v 2. A school -slate, in combination with a frame comprising an inner supporting-case made from astrip of sheet metal or equivalent material of proper width and length, cut to form the corners,with' mitered sides, rounded edges, and the narrow connecting-strip over each corner, then bent and fastened over the edges of said slate, and an outer coating of rubber or similar elastic material enveloping said case and extending under the edges thereof, substantially as shown and specified. 3. The method of making and attaching a frame to a school-slate, consisting in cutting and bending a strip of sheet metal or equivalent material of proper width and length into the proper form to produce an inner supporting-case having rounded corners, mitered at the sides, and a narrow connecting-strip over each corner, then fitting said case over the edges of the slate with the ends thereof brazed or soldered together, then enveloping its outer surface with unvulcanized rubber, extending the same under the edges thereof, and finally subjecting said coated case or frame to pressure and heat between suitable molds and in contact with sulphur, thereby causing the rubber to be molded, vulcanized, and to adhere tightly to the metal casing, as well as to the edges of the slate, substantially as and for the purposes set forth.

DAVID SORYMGEOUR.

'Witnesscs:

R. C. PENNEY, W. E. J ONES.

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