US3389520A - Sandwich drafting board structure - Google Patents

Description

June 25, 1968 H. w. GRAY ET AL 3,3 9,

SANDWICH DRAFTING BOARD STRUCTURE Filed April 6, 1966 United States Patent SANDWICH DRAFTING BOARD STRUCURE Harold W. Gray, Toronto, Ontario, and Arthur L. W.

Watt, Willowdale, Ontario, Canada, assignors to The Hughes-Owens Company Limited, Montreal, Quebec,

Canada Filed Apr. 6, 1966, Ser. No. 540,628 3 Claims. (Cl. 52-309) ABSTRACT OF THE DISCLOSURE The invention comprises a drafting board having a core formed of expanded plastic composition foam, a rigid cover sheet is applied to each major side surface of the foam core and, on one side of the board a sheet of resilient material, such as linoleum, is fixed to constitute the drafting surface.

This invention relates to table top structure and particularly to drafting board structures which avoid the difficiencies of wooden boards and at the same time yield the requisite lightness and dimensional stability.

Conventional wooden drafting boards are known to be relatively expensive and inherently subject to warpage and swelling upon alternate exposure to moist and dry arr.

Accordingly it is an object of this invention to provide a light and rigid table top, particularly suitable for use as a drafting board, which maintains its original flatness and dimensional stability regardless of the conditions of air in which it is used.

We have found that it is possible to devise such a stable board structure through the use of a layer of relatively stiff foamy material sandwiched between two sheets of rigid material. Preferably, we provide a frame around the edges of the assembly to give it the desired structural rigidity, and glue the sheets to the layer of foamy material.

Summary 0 the invention The present invention resides in a drafting board comprising a rectangular sheet of expanded plastic composition foam. A rectangular frame is fixed to the edges of the foam sheet and a rigid sheet is applied to each major side surface of the foam sheet. A sheet of resilient material, such as linoleum, is fixed to one of the rigid cover sheets in completely overlying relation to the foam sheet to constitute a drafting surface.

In the drawings which illustrate an embodiment according to the present invention,

FIGURE 1 is a perspective view of a drafting board and FIGURE 2 is a cross section taken along line IIII in FIGURE 1.

Referring to FIGURE 1 of the drawings, reference numeral 1 indicated generally a drafting table top mounted on a support 2 which includes a pair of legs 3 each having a pivotal connection arrangement 4 to couple the legs 3 to the table top 1 so as to allow angular adjustment thereof about the longitudinal axis of the table top 1. The front edge In of the drafting table top I is provided with a pencil rack 5. Such supports and pencil racks are well known in the art and any conventional design thereof ice may be used in connection with table top structures according to the present invention.

As shown in FIGURE 2 of the drawings the structure of the present table top I essentially comprises a layer of low density, relatively stiff and preferably non-permeable foamy material 6 such as expanded plastic, sandwiched between two sheets of rigid material 7, and frame members 8 disposed around the assembly so as to give it more structural rigidity. The edges of the sheets 7 are secured to the rigid members 8 by any suitable fastening means such as rivets or bolts 9, and the intermediate portion of the sheets 7 are preferably glued to the layer 6.

Channel members 10 may be disposed around the outer edges of the frame 8 so as to overlie margins of the sheets 7. The channel member 10m at the front of the table top I may be shaped so as to form the pencil rack 5. Finally, a layer 11 of firm but resilient material is applied to the top surface of the table so as to cover the upper sheet 7 to provide a good drawing surface.

In a preferred embodiment the layer of foamy material 6 consists of expanded polystyrene plastic such as known under the trademark Styrofoam, and the sheets 7 are made of aluminum. Frame members 8 may be a properly shaped aluminum extrusion or pieces of plywood secured to the upper and lower sheets 7.

The channel members 10, preferably aluminum, trim the outer edges of the assembly and are secured thereto by means of rivets, or wood screws when frame 8 is made of plywood. The covering 11 of the upper surface of the drafting board may be a layer of linoleum which is known to provide a satisfactory drawing surface.

Pieces of plywood, plastic or metal may be used to provide rigid structural members across the board or along its length as required.

What we claim as our invention is:

1. A drafting board comprising a rectangular sheet of expanded plastic composition foam, a rectangular frame fixed to the edges of said sheet, a rigid sheet completely overlying and engaging each major side surface of said foam sheet, means securing said rigid sheets to said frame, said means including channel members overlying the edges of said frame and the marginal portions of said rigid sheets and a sheet of resilient material engaging and fixed to one of said rigid sheets and completely overlying said foam sheet.

2. A drafting board as defined in claim 1, wherein said foam sheet is a polystyrene resin.

3. A drafting board as defined in claim 1, wherein said resilient sheet is linoleum.

References Cited UNITED STATES PATENTS 2,066,718 1/1937 Dietz 52-623 X 2,612,423 9/1952 Hennell 1089O 2,664,596 1/1954 Greig 52624 X 2,911,274 11/1959 Grube 52-623 X 3,147,336 9/1964 Mathews 52-615 X 3,182,767 5/1965 Kuehl 52-6 27 X 3,219,383 11/1965 Nerern 52-627 X 3,235,040 2/1966 Ellis 52623 3,323,797 6/1967 Horton 52-615 X DAVID J. WILLIAMOWSKY, Primary Examiner.

' D. L. TAYLOR, Assistant Examiner.

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