US2809403A

US2809403A - Structural panel and method of making the same

Info

Publication number: US2809403A
Application number: US498281A
Authority: US
Inventors: Clements Macmillan
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-03-31
Filing date: 1955-03-31
Publication date: 1957-10-15
Anticipated expiration: 1974-10-15

Description

Oct. 15, 1957 MacMlLLAN CLEMENTS 2,309,403

STRUCTURAL PANEL ANDMETHOD OF MAKING THE SAME Filed March 51, 1955 1,9 INVENTOR.

Mae M71102 C/eme 2,809,403 Fatented Oct. 15, 1957 STRUCTURAL PANEL AND METHOD OF MAKING THE SAME MacMillan Clements, Ridgefield, Conn.

Application March 31, 1955, Serial N 0. 498,281

2 Claims. (Cl. -91) This invention relates to structural panels, and more particularly to the structure of a door composed of such panels.

An object of the invention is to improve the structural characteristics of a panel, particularly the core thereof, in order to obtain maximum strength when using a core composed of comparatively thin single or laminated sheets.

Another object of the invention is to provide an improved method of making a door of the type set forth in the next preceding paragraph above.

Other objects will appear hereinafter throughout the specification.

In the drawings:

Figure 1 is a partly broken away perspective view of one embodiment of the invention;

Figure 2 is a perspective view of certain of the parts shown in Figure 1 and with the stiles separated from the core;

Figure 3 is a perspective view of the door showing a typical manner for compressing the core;

Figure 4 is a broken away view of the core and a vertical sectional view of the rollers shown in Figure 3;

Figure 5 is a broken away view with the covers about to be applied to said core, the covers being shown in vertical section;

Figure 6 is a top plan view of one form of core in place on the bottom cover;

Figure 7 is an enlarged view of a single cell of the core of Figure 6, showing grid cuts therein and the cutters for making said grid cuts; and

Figure 8 is a second form of grid, partly broken away, showing grid cuts therein, and the cutters for making said grid cuts.

Following the successful production and use of the so-called honeycomb grid type of door wherein the grid or core has been compressed during one of the manufacturing steps thereof to thereby impart better bonding between core and cover sheets, as disclosed in my prior Patent No. 2,511,620, granted June 13, 1950, various attempts have been made to obtain the improved results of said patented door, but at a reduced cost, see Interior Flush Doors with Standard Honeycomb Cores, Service Bulletin H-3, published by Union Bag and Paper Corporation, Honeycomb Division, October 6, 1954.

The grid or core of such doors is composed of a plurality of single strips of paper, as distinguished from a grid composed of strips each composed of a central corrugated paper member provided with cover members of paper as shown in Figure 3 of the aforementioned patent.

When a grid composed of a plurality of single strips of paper, as set forth in said Union Bag and Paper Corporation publication, is subjected to a crushing or pressure treatment as therein described in order to bring it to size and shape it to fit proper thickness of stiles and rails, its internal, i. e., the honeycomb structure, is greatly weakened. In other words, in order to accomplish the results which have been definitely established in the construction shown in the aforementioned patent, wherein a section of corrugated material is used between sheets of paper to form a grid, allowing for compression without distortion or injury to the structural entity of the core, substitute materials of lesser order are being offered to the trade, as set forth in the aforementioned publication, and it has been found that when using said substitute materials, the door composed in part of said materials loses a major part of its structural characteristics.

The corrugated box-board core material of said patent, when subjected to compression, has a tendency to splay outwardly, thereby establishing even more firmly a true bond between its upper and lower side edges and the surfaces of the inner and outer sheets to which they are attached. However, grids composed of sheets of very thin material, as taught in said publication, and wherein the grid composed of said sheets is crushed, it has been found that the crushing operation causes the sheets to bend or become S-shaped in cross section, thereby destroying the major structural characteristics of the socalled honeycomb type of core, and weakening the bond between said core and the cover sheets which are fastened thereto.

The present invention is directed to the use of very thin sheets of single or multiple material and to the method and article which includes the pre-slicing or cutting of the extra thickness of the core so that a series of small foldable flanges are formed by a pressing or rolling means. These flanges increase the surfaces which are bonded to the cover sheets and the said flanges make it possible to provide substantially straight connecting sweeps between the cover sheets which sweeps form the major part of the grid.

In the drawings, the numeral 16 indicates the rectangular frame which is composed of the rails or side pieces 12 and the stiles or end pieces 14. Connected to the frame by any suitable means are the front cover 16 and the back cover 18, as shown in Figure 1. The frame is provided with the usual solid wood block 29 for receiving a lock that is glued or otherwise fastened to the inside of one of the rails. The opposite rail is provided with blocks 22,

The grid as a whole is indicated by the reference numeral 24. This is composed of a plurality of crossed or interlocked sheets of comparatively thin paper, which latter may be composed of single sheets or of laminated sheets 26. The grid sheets cross each other to form diamond shaped openings and may be suitably notched for this purpose, as shown for instance in Figure 3 of my patent mentioned above. The sheets are compressed by the blocks as and 22 when they are placed within the frame 10. The parts of the

frame

12 and 14 and the

sheets

16 and 18 may be attached to each other by any suitable means such as nails, glue, or both, not shown.

Prior to the insertion of the core 24 within the framework, the sheets are subjected to a series of cutters indicated by reference numeral 28 in Figure 8, which cutters, when they pass over the grid, cut a series of slots 30, as shown in Figure 8.

The distance of the cut is the same or substantially the same as the distance that the core projects beyond the frame on opposite sides thereof. in other words, the core may project one-sixteenth or one-thirty second of an inch on opposite sides of theframe, and the depth of the cut on the opposite sides of the core in the case of a projection of one-sixteenth of an inch will be onethirty second of an inch on opposite sides thereof.

Following the cutting operation, which has been diagrammatically illustrated in Figure 3, the grid is assembled within the frawework it and both sides thereof are subjected to a compression action by passing the frame with the grid therein between the rollers 32, as diagramthe upper flange and the bottom surface of the lower flange, as viewed in Figure 4.

Cover sheets

16 and 18 are then applied to opposite sides of the framework, and the core, which is under slight compression, presses the flanges 34 against the inner surfaces of the

cover sheets

16 and 18 to thereby cause the same to adhere to said inner surfaces thereof. It will be noted by reference to Figures 4 and 5 that the sheets 26 are substantially straight, because they have not been buckled or formed into S- or C-shape by the compressing operation. This is due to the fact that the core has been slit at'nurnerous points to form the slots 30, and that the rollers merely bend over the flanges 34 and only apply an infinitesimal amount of pressure to the vertical portionsof the grid.

Referring to Figures 6 and 7, a truly honeycomb, type of grid has been shown therein. This grid is formed of a plurality of cells 36 and the sides of the cells are formed with slots 38 by the cutters 44) which are caused to pass over the honeycomb grid so as to form the slots on both the upper and lower edges thereof.

One manner of forming slots in both the upper and lower portions of any of the grids shown in the figures, is to first pass a gang of cutters, such as shown at 28 or 4 as would occur to one skilled in the art to which the invention relates.

I claim: 7

1. A method of making a structural panel comprising the steps of providing a flat cellular core having the cells thereof polygonal in cross section and defined by peripherally extending walls'and open ends, providing said walls at both ends of each cell and adjacent the corners thereof with slots, providing a flat rectangular frame of less overall thickness than said core, fitting said core into said frame with each of its side faces disposed outwardly of theadjacent side face of said frame, bending the portions of said cell walls between said slots at right angles to the remaining portions of said walls to form flanges whose outer faces are substantially flush with adjacent side faces of said frame, applying adhesive to said outer faces of said flanges, and securing a cover sheet to each 40, over the grid as it rests on a flat'surface, whereupon 7 the grid is turned over and the gang of cutters is passed over the now upper surface forming the grid.

It will be understood that the grid composed of cells such as those shown in Figures 6 and 7 will be compressed by rollers of the same type as that shown in Figure 3, so as 7 various alterations and modifications may be made such 4 side of said frame and said flanges.

2. A door construction comprising a flat rectangular frame, a flat cellular core fitted into said frame, the cells of said core being polygonal in cross section and open at their ends, said cells extending transversely of said core, each cell having. Walls, each Wall having at least two slots, the part of each wall between the slots comprising a right angled flange arranged in parallel relation to the plane of the core, the flanges at each end of each cell being separate from each other, and a cover plate secured to eachside face of said frame and said core including, said flanges, said'core being compressed substantially equally on both sides and having a resiliency tending to force its side faces outwardly into engagement attaching said flanges to the cover plate located adjacent thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,511,620 Clements June 13, 1950 2,537,026 Brugger Jan. 9, 1951 FOREIGN PATENTS 7 56,227 Sweden Mar. 11, 1924 60,158 France Mar. 24, 1954 (Addition to No. 988,034.)