US2595087A

US2595087A - Load retaining door

Info

Publication number: US2595087A
Application number: US37417A
Authority: US
Inventors: John H Leslie
Original assignee: Signode Steel Strapping Co
Current assignee: Signode Corp
Priority date: 1948-07-07
Filing date: 1948-07-07
Publication date: 1952-04-29
Anticipated expiration: 1969-04-29

Description

April 29, 1952 J. H. LESLIE, I!

LOAD RETAINING DOOR 3 Sheets-Sheet 1 Filed July 7, 1948 April 29, 1952 J. H. LESLIE, I:

LOAD RETAINING DOOR 3 Sheets-Sheet 2 Filed July 7, 1948 v l/lI/lllilllllli' illlll'llll x w z arr-7:717 mm go 924,

April 29, 1952 J. H. LESLIE, ll

LOAD RETAINING DOOR 3 Sheets-Sheet 3 Filed July 7, 1948 ea/Zel Patented Apr. 29, 1952 TATES ATENT OFFICE 11 Claims. 1

My invention relates to load retaining doors.

More particularly it relates to what has popularly, although much too narrowly, become known as grain doors, because such doors were first used in the bulk shipment of grain in railway cars. As a matter of fact, such doors are equally well adapted to close (or usually more properly speaking, partly to close) doorways to bulk-load occupying spaces in a wide range of fields other than grain such for example; as minerals like cement, clays, ground limestone, potash, talc, salt, silica sand and granulated slate; as chemicals like alumina, resin and zinc oxide; and as a variety of miscellaneous prod-- ucts like ground corn cobs, cottonseed, sawdust, bentonite, peanuts, gravel, gypsum, mica, sulphur, and others too numerous to mention.

In, for example, the shipment of grains in box cars, the first inner or retaining doors, as distinguished from the outer ordinary car doors, were in the form of wooden bulkheads. Such doors were expensive and otherwise objectionable but for many years there was no satisfactory substitute. The first satisfactory substitute in which paper or other fabric was substituted for wood is disclosed in the Herbert Corkran Patent No. 2,116,260 of May 3, 1938. The Corkran patent door marked a distinct advance in the art but it had the objection, like the wooden bulkhead, of requiring fabrication at the car or on the job. The next improvement was what may be termed the prefabricated fabric door of the John M. Moon Patent No. 2,310,860 of February 9, 1943 which permitted supplying car loaders with ready-built door assemblies requiring relatively little work on the job.

Although for many situations doors of the Moon patent type were a decided advantage over doors of the Corkran patent type, because they were prefabricated, the doors of the Moon patent type did not lend themselves to large scale factory productions on standard types of socalled combining machines with which the paper industry is equipped and familiar.- This is for the reason that the employment, in the construction of the paper panel, of an inner ply narrower than the outer ply to leave lengths of the spaced steel cross-straps uncovered so that the nail holes are visible to installers, made it uni'easible, if not practically impossible, to feed in the metallic cross-strap strips during the longitudinal high speed passage of" the paper webs through the rolls of a combining machine- In other words, the use of plies of difierentwidth to form the closure panel of a door required that:

the width of the wider ply correspond to doorway width (plus the desired doorway overlap). This requirement made it necessary that, as the long paper webs pass through the combining machine in the process of assembling the plies and sticking them together, the flexible steel crossstraps, cut to predetermined lengths corresponding to car doorway widths, be applied or fed in between the plies at properly spaced intervals and at right angles to the direction of movement of the long webs.

Such amethod of assembly presents problems which would not be met could the long webs of paper or other fabric and the necessary spaced metallic cross-straps inthe form of long steel ribbonsbe both fed through the combining machine in the same manner and in a common longitudinal direction.

'lhe principal object of my invention is to provide afabric panel doorway-closure assembly which, while affording excellent indicia for 10- eating nail holes through the metallic crossst'raps, lends itself to production in combining machines of usual standard types;

Another object is to provide a method of as sembling long webs of parallel plies of fabriclike' material and interposed metallic cross-strap flexible ribbon and causing them to stick toget-her so that by cutting the composite web to' lengths corresponding to doorway widths Dre-- fabricated load-retaining doors may be expedi tiousl-y produced.

A further object is to provide a door wherein, although cross-strap nail hole locations may beeasily identified, both visually and by the sense of touch, neither the cross-straps nor any part of them, nor the nail holes therethrough, are uncovered;

Other objects and advantages will hereinafter appear.

Typical embodiments of my invention as exemplified in a door and equipment suitable for carrying out the method of making it are illustrated in the accompanying. drawings wherein:

Fig- 1 is an inside elevation of a door in place acrossthe doorway ofa railwaycar;

Fig. 2 is an enlarged perspective in section of a portion of the fabricply metallic cross-strap panel assembly; I

Fig. 3 is a diagrammatic representation of a combining machine whereby the process of assembling the plies and cross-straps and causing the cross-strap nailholes to register themselves in one" of the plies may be: carried out;

Fig. 4 is an enlarged perspective in section of a modified construction of composite panel;

Fig. 5 is an enlarged cross sectional view of how the cross-strap nail holes register themselves in one of the fabric plies during the assembling process;

Fig. 6 is an enlarged perspective in section of another modified construction which, under many conditions, has been found to be the most desirable arrangement; and

Fig. 7 is a cross section through a portion of the assembly shown in Fig. 6.

In general, my invention comprehends a composite multi-fabric ply and interposed spaced metallic perforated cross-strap panel adhering together to form a unitary whole in which the fabric plies are substantially coextensive and completely conceal the cross-straps and yet ply irregularities registering with the cross-strap perforations (nail holes) render the locating of the concealed perforations an easy matter, and a method or process whereby such composite door panels may be readily manufactured by essentially standard factory equipment familiar to the paper industry.

Referring first to Figs. 1 and 2, my prefabricated door A is shown in place inside a railway car to close the doorway B. The door bridges the doorway to the desired load height and overlaps the vertical doorway side posts If) and l I to which it is secured by suitable means generally and herein designated as nails. A head strip l2, generally of Wood, may be nailed across the doorway at the top of the door to protect it against injury from such as the spouts of loading and unloading machinery or the climbing out of the installer after both car doors have been closed. A foot strip 13 may likewise be nailed across the dorway at the bottom of the door and preferably a suitable length of the door panel, after being reinforced by such a foot strip, is brought inwardly to form an apron or floor flap 14 which may be nailed to the car floor in essentially the manner in which the sides of the panel are nailed to the doorway side posts as will be hereinafter explained.

The door selected for illustration consists of two plies-an inner ply l5 and an outer ply 16- of a suitable relatively inexpensive fabric such as paper. The inner and outer plies are substantially coextensive. In the production of these fabric panels, as will be later explained, the width of the plies is made the height the door is to fill the doorway plus whatever may be neded for an apron M if the door is provided with such an apron. The other dimension of the pliesthat is in doorway width direction-is such as to bridge the doorway and overlap the side posts H] and II sufficiently to enable the cross-straps effectively to be attached thereto.

interposed between the inner and outer fabric plies are a series of spaced supporting metallic cross-straps l1. These straps are substantially as long as the door panels are wide and spaced apart suiiiciently to afford the necessary load resisting qualities without undue expense and weight. Usually the spacing can be increased gradually from a region at or near the bottom toward the top. Each cross-strap is perforated at regular properly spaced intervals with nail holes is through which nails can be driven into the doorway posts.

For railway car grain doors, fabric plies of kraft calendared finish paper of a thickness of approximately .010", having a linear strength of about pounds per inch of width and a crossmachine strength of about 50 to 55 pounds per inch; cross-straps of A" x .020" cold rolled mill steel with nailing holes for 8d steel wire nails with approximately center-to-center spacing, have been found in practice to give uniformly satisfactory results.

The inner and outer plies and the spaced flexible metallic perforated cross-straps interposed therebetween are made to cling to each other by sticking them together into a unitary whole with a thin layer 19 of suitable adhesive such as asphalt.

Now since the cross-strap nail holes are covered by the paper plies of the panel, it is necessary to indicate their location so that they may be readily found by the installer. And since the attaching nails must frequently be applied in relative darkness, such as is the case with the second-to-be-closed of the two doors of a railway car, it is desirable that they can be accurately located by the sense of touch as well as visually. This result I accomplish by providing at least the inner ply with irregularities of surface which register with the nail holes of the cross-straps. All of the nail holes of the crossstraps need not be thus in register with irregularities in a panel ply but only those in the end regions of the straps where the nails must be located to find anchorage in the sides of the car doorwayfor example, in the doorway side posts 10 and I l.

Preferably these nail hole indicating irregularities are in the form of what may be termed dimples (depressions) or pimples (projections) in registry or alignment with and substantially the same size as the nail holes. By forming them either to project or in the shape of slight cavities, they can be easily felt and located by the sense of touch as well as by the eye.

Thus referring especially to Fig. 2 the inner ply i5 is indented into cross-strap nail holes [8 so as to form a series of dimples or shallow cup-like depressions 20 foreach door-at least in those regions adjacent its side edges where attaching nails must be driven-each depression marking a spot where a nail may be driven through a hole in a cross-strap. Not only are the strap holes readily located but because there need be no holes in either ply and the cross-straps are entirely covered, there are no holes through which load particles, such as grain kernels, can pass and the metallic cross-straps are not exposed to the weather. Furthermore, the preforming of the nail holes in the cross-straps enables aligning them accurately along the center line with the result that driven nails are also accurately centered which aids in insuring maximum strength efficiency of the fabric plies.

Such prefabricated composite door panels, manufactured in a few standard sizes of heights, to correspond to usual heights of bulk loads, and of widths, to correspond to standard car widths, may be readily installed even in dark places because, by the sense of touch as well as by sight, the operator can readily locate cross-strap nail holes over places where nailing will be most effectivesuch as over the doorway side posts and, if aprons are used, into the car floor. The points of the nails can be used to find, if the operator cannot readily see, the places where nails can be driven through nail holes in the load bearing cross-straps.

The fabrication of complete unitary load retaining doors of the type shown in Figs. 1 and 2 and just described may be carried out with simple standard like combining machines because both the fabric plies and the metallic crossetraps can be brought together and fed continuously through and over rollers in a manner well-known in the paper industry. This is for the reason that the plies, being coextensive, can be fed through a combining machine as long webs of a width correspondin to door height (plus somethin for an apron M if desired) and the spaced metallic cross-straps between plies can likewise be fed through the machine in the form of long ribbons. Ability to feed the cross-straps in the direction of the movement of the fabric plies facilitates the often desirable difference in cross-strap spacingbetween top and bottom of doors heretoforementioned and the maintenance of desired spacing. The composite web thus produced can be out, either as a continuation and part of the assembling process or, later, to lengths corresponding to standard doorway widths plus whatever is deemed desirable for overlapping the regions where nails can be driven into satisfactory anchorage.

Fig. 3 shows diagrammatically a combining machine for accomplishing this method of assembly and for producing the strap nail hole markings.

This machine has supports, not shown, for a roll of a paper web which will form the inner ply l5, for a roll 25 of a paper web which will form the outer ply l6, and for a series of coils 21 of perforated flexible metallic ribbon which will constitute the cross-straps H. Th ply-

webs

25 and 25 with spaced cross-strap ribbons 21 interposed therebetween are fed to a combining roller 39 where they are united to constitute a composite web. Between the web supply rolls 25 and 2 5 and combining roller 36 the two webs of paper are coated on the inner surfaces with a thin layer of an appropriate adhesive, such as asphalt, derived from suitable pots and 36. Scrapers 3'! and 33 may be employed if desired to facilitate application of a uniform layer of adhesive and. to remove excess. ing roller as the composite web of paper plies and interposed metal cross-strap ribbons passes intermediate rollers such as indicated at i9, 3! and 32 where, by suitable cooling, tension, and pressure, or otherwise, the desired intimate contact and close and firm adhesion is insured. From the last intermediate roller 42 the composite web passes between a rubber or rubber surfaced roller t3 and a steel roller 44. As the composite web passes between rollers 43 and 44, sufficient pressure is impressed upon those rollers, or one of them, to cause the surface of roller 63 to become distorted momentarily upon the passage of each covered nail hole and enter a short distance therein, forcing the inner ply I5 to follow in a restricted area. In other words, the steel roller i l acts like an anvil to support the composite web while the rubbersurface of roller t3 acts similar to a series of transient punches to force small areas of the inner ply l5 into the underlying strip perforations (nail holes) which act similar to a series of dies. In this manner throughout its whole length, or, by the use of segment rollers only in limited zones at regular intervals where the composite web will be cut into sections of door width, the inner ply of the composite web will be provided with cupshaped depressions or dimples registering with and indicating the presence therebelow of concealed nail holes through the completely cov- From the combinr ered cross-straps. From the impression rollers 43---% the composite web may be fed directly to a suitable cutter roll 45 which will sever it into doorway-width lengths, or the composite web may be reeled into a suitable roll for subsequent cutting.

Instead of forming the nail hole indentations or small cavities or dimples in the inner ply they may be in the form of small projections or pimples in the inner ply which register with the cross-strap nail holes.

Such an arrangement is indicated in Figs. 4 and 5 wherein the inner ply projections registering with and defined by (and also defining) the nail holes serves as the indicia of nail hole 10-- cations in the concealed cross-straps. Such an arrangement can be produced by applying the rubber or rubber surfaced roller 43 against the outer ply it instead of against the inner ply, and relieving the steel roller, as at 5|, so that the inner ply 15 may be forced outwardly as the momentarily formed punches in the surface of the rubber roller 43 act upon the outer ply side of the composite web.

The modification illustrated in Figs. 6 and '7 is provided with nail hole locating indicia which may be of a sort of combined pimple and dimple type. In this construction, instead of cleanly perforating the cross-strap ribbon to form the spaced nail holes therethrough, the punch and die combination whereby the holes through the strap are formed is so related that in the punching operation a small upstanding flange is made to surround or frame each nail hole. In th combining operation, which is performed substantially as heretofore described with special reference to Fig. 3, the cross-strap ribbon is fed in between the ply webs of paper in such a way that the little upstanding circular flanges 55 are next to the inner ply l5. When thus assembled, passage through the machine results in these small circular upstanding flanges indenting, possibly even completely cutting, the inner ply so as to produce, in effect, circular embossments of the inner ply registering with and surrounding the nail holes through the cross-strap ribbons. And, if a rubber or rubber faced impression roller is used, the surface of the roller will be locally and momentarily distorted as the flanged nail holes pass thereagainst so that within the area defined by the hole-framing flanges the inner ply may be slightly cupped inwardly. If desired, both impression rollers may be metal surfaced. These circular embossments, serving essentially the same purpose as the previously described pimples or dimples, provide effective indicia enabling the installer to locate nail holes in the concealed crossstraps both by the eye and by the sense of touchan effect which will be enhanced if the inner ply is slightly depressed or cupped within the area defined by the hole flanges. Even if the cutting effect produced between the nail hole framing flanges and the impression rollers be sufficient to cut through the inner ply, still the nail holes are not thereby opened so that load particles may leak therethrough because the outer ply, which will remain uncut, will cover them.

Having thus illustrated and explained several embodiments of my invention, what I claim and desire to secure by United States Letters Patent is as follows:

1. A load-retaining door comprising at least two superposed substantially coextensive plies of fabric of a width somewhat in excess of doorway width; a plurality of spaced metallic cross-straps,

which are perforated to receive nails for attaching the cross-straps to a doorway frame, interposed between and substantially covered on both sides by two of the plies; and an adhesive for binding the fabric plies and cross-straps together into a unitary whole; characterized by one of the plies being provided with irregularities which register with perforations in the covered crossstraps to indicate the locations thereof.

2. A prefabricated load-retaining door comprising at least two substantially coextensive superposed plies of fabric of a width somewhat in excess of doorway width and of a height appropriate for load height; a plurality of spaced metallic cross-straps interposed between the plies of fabric and extending in substantially parallel relation across the entire width of the door, at least some of the cross-straps having a line of spaced nail holes therethrough which are covered by the fabric; and means for uniting the fabric plies and cross-straps into a unitary whole; characterized by substantially. circular irregularities in one of the plies which register with nail holes in the cross-straps whereby the nail holes are indicated although covered.

3. A prefabricated load-retaining door comprising at least two substantially coextensive superposed plies of fabric of a width somewhat in excess of doorway width and of a height appropriate for load height; a plurality of spaced metallic cross-straps interposed between the plies of fabric and extending in substantially parallel relation across the entire width of the door, at least some of the cross-straps having a line of spaced nail holes therethrough which are covered by the fabric; and means for uniting the fabric plies and cross-straps into a unitary whole; characterized by depressions in one of the plies registering with nail holes in the cross-straps to enable locating the positions of nail holes although they are covered.

4. A prefabricated load-retaining door comprising at least two substantially coextensive superposed plies of fabric of a width somewhat in excess of doorway width and of a height appropriate for load height; a plurality of spaced metallic cross-straps interposed between the plies of fabric and extending in substantially parallel relation across the entire width of the door, at least some of the cross-straps having a line of spaced nail holes therethrough which are covered by the fabric; and means for uniting the fabric plies and cross-straps into a unitary whole; characterized by dimples in one of the plies which register whereby nail holes may be located although concealed.

5. A prefabricated load-retaining door comprising at least two substantially coextensive superposed plies of fabric of a width somewhat in excess of doorway width and of a height appropriate for load height; a plurality of spaced metallic cross-straps interposed between the plies of fabric and extending in substantially parallel relation across the entire width of the door, at least some of the cross-straps having a line of spaced nail holes therethrough which are covered by the fabric; and means for uniting the fabric plies and cross-straps into a unitary whole; characterized by outstanding flanges framing, the cross-strap nail holes and embossing one of the plies to indicate locations of the concealed nail holes.

6. A prefabricated load-retaining door com.- prising at least two substantially coextensive with nail holes in the cross-straps superposed plies of fabric of a width somewhat in excess of doorway width and of a height appropriate for load height; a plurality of spaced metallic cross-straps interposed between the plies of fabric and extending in substantially parallel relation across the entire width of the door, at least some of the cross-straps having a line of spaced nail holes therethrough which are covered by the fabric; and means for uniting the fabric plies and cross-straps into a unitary whole; characterized by outstanding projections which at least partially frame the cross-strap nail holes and emboss one of the plies to indicate locations of concealed nail holes.

7. A prefabricated load-retaining door comprising at least two substantially coextensive superposed plies of fabric of a width somewhat in excess of doorway width and of a height appropriate for load height; a plurality of spaced metallic cross-straps interposed between the plies of fabric and extending in substantially parallel relation across the entire width of the door, at least some of the cross-straps having a line of spaced nail holes therethrough which are covered by the fabric; and means for uniting the fabric plies and cross-straps into a unitary whole; characterized by outstanding projections which at least partially frame the cross-strap nail holes and mark one of the plies thereabout so that hole locations are indicated although the holes are covered.

8. A prefabricated load-retaining door comprising at least two substantially coextensive superposed plies of fabric of a width somewhat in excess of doorway width and of a height appropriate for load height; a plurality of spaced metallic cross-straps interposed between the plies of fabric and extending in substantially parallel relation across the entire width of the door, at least some of the cross-straps having a line of spaced nail holes therethrough which are covered by the fabric; and means for uniting the fabric plies and cross-straps into a unitary whole; characterized by pimples in one of the plies which register with nail holes in the cross-straps whereby nail hole locations are indicated although the holes are concealed.

9. A prefabricated load-retaining door comprising at least two substantially coextensive superposed plies of fabric of a width somewhat in excess of doorway width and of a height appropriate for load height; a plurality of spaced metallic cross-straps interposed between the plies of fabric and extending in substantially parallel relation across the entire width of the door, at least some of the cross-straps having a line of spaced nail holes therethrough which are covered by the fabrics; and means for uniting the fabric plies and cross-straps into a unitary whole; characterized by outstanding flanges framing the cross-strap nail holes and embossing one of the plies and by shallow cavities in the embossed ply within the areas defined by the flanges whereby the locations of concealed nail holes are indicated.

10. A load retaining strip comprising at least two juxtaposed substantially coextensive plies of fabriclike material, a metallic load bearing crossstarp interposed between the plies and extending between two of the edges of the multi-ply strip, the cross-strap having spaced perforations therethrough which are covered by the plies on opposite sides thereof, and an adhesive for uniting the adjacent faces of the plies and the crossstrap into a unitary whole, characterized by one of the plies being provided with surface irregularities which register with cross strap perforations to indicate the location of the perforations covered thereby.

11. A load retaining strip comprising at least two juxtaposed substantially coextensive plies of fabriclike material. a metallic cross-strap interposed between the plies and extending between two of the edges of the multi-ply strip, the crossstrap having spaced perforations therethrough which are covered by the plies on opposite sides thereof, and an adhesive for uniting the adjacent faces of the plies and the cross-strap into a unitary whole, characterized by one of the plies being provided with surface ridges registering with and defining perforations in the cross-strap to indicate the locations thereof.

JOHN H. LESLIE, II.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,096,579 Wardell May 12, 1914 1,863,186 Burns June 14, 1932 2,297,607 Blackburn Sept. 29, 1942 2,310,860 Moon Feb. 9, 1943 2,372,617 Trew Mar. 27, 1945 2,427,229 Riley Sept. 9, 1947 2,438,764 Phillips Mar. 30, 1948 2,446,524 Brennan Aug. 10, 1948