US1517528A - Metal box-corner fastener - Google Patents

Description

'eg, 2, 1924.v

A. E. BLACKMAN METAL BOX CORNER FASTENER Filed April 23 1921 m A m Wm 15M H m m STAES PATENT oFFi f ALBERT E. BLACKMAN, OF NEW YORK, N. Y.

METAL BOX-CORNER. FASTENER.

Application filed April 23, 1921. Serial No. 464,018. I

To all whom it may concern:

Be it known that I, ALBERT E. BLACKMAN, a citizen of the United States, residing at New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Metal Box-Corner Fasteners, of which the followin is a specification.

lVly invention relates toimprovements in metal box Construction and more particularly to boxes used to encase electrical switches or other electrical devices commonly known commercially as metal switch boxes.

The customary procedure when assembling or forming boxes of this character is to bend the side and end walls to their upright position and hold each corner with a pair of pliers or other suitable means until the spot-weld or rivet has been applied. The result of this mode of forming up boxes is very unsatisfactory, because it will be understood that heavy gauge metal is naturally springy and the tendency of the walls when bent upright is to spring outward so that the operator is required to hold the.corners in place until the spot-weld has been applied. This task is not at all easy and the corners often slip out of true while being welded, which results in an uneven box.

The object of the present invention is to provide means whereby the side walls of a metal box, of the character hereinafter described, may be securely attached together without the use of spot-welding or rivets.

A still further object of the invention is the provision of a box-blank of heavy gauge Fig. 3 is a perspective view of one cornerof the box showing the end wall before it is locked in upright position.

Fig. 4, is a plan view of the development or blank of one corner of the box.

Referring to the drawing 10 denotes the body of a switch-box having a suitable cover 11, hinged on ears l2, projecting from one end of the upper portion of the body of the box 10. The side walls 13, and end walls 14, are bent upright from the bottom 15. The edges of the end walls are provided with extensions or ears 16, which are adapted to be bent at right angles to the end walls and are provided with suitably shaped tongues 17. The free edge of each tongue is preferably raised slightly beyond the plane of the remaining portion of the ear and lies parallel thereto, so that when the ear is brought into position the tongue 17, will be projected into the interior of the box. It will be noted with reference to the drawing that the arcuate cut in each of the ears 16, forming a tongue 17, begins and ends at the bend forming the corner of the. box, so that when the box is assembled the free edge of the tongues will be disposed toward the center of the side walls 13.

Adjacent the front and rear edges of the side walls 13, a pair of oppositely extending tongues 18 and 19, are arranged, one being disposed above the other. These tongues 18 and 19 respectively, are also bent beyond and then parallel to the walls so. that when the side walls are in upright position the tongues will be projected into the interior of the box.

It will be apparent that should the upright walls of the box-form be of such height that one group of interlocking tongues would not be sufficient to securely hold the walls in their proper place, any adside walls 13 and end walls 14, are raised to a vertical position. The cars 16 will ride in on the inner face of the side walls until the straight edges of the ears 16 abut the I closed end of the upper tongues 18 bn the side walls 13, and at this point the lower tongues 19 w1ll have entered the space left by the tongues 17 on the ears 16. The free edges of the lower tongues 19 in the position just described, will be seated against the edge of the cut left by the inwardly bent tongues 17 upon the ears 16. It will be noted that when the sides of the box are interlocked by means of the tongues 18 and 19, respectively, with the end wall 14, that it is practically impossible to move the latter walls either inwardly or outwardly If it is further desired to more securely attach the walls together at the corners a spot-weld may be applied, but in practice it has been found that the metal is of suflicient stifiness to assure the permanent locking of the walls and will withstand the most severe strains without becoming disengaged. The overlying portion of the upper tongues 18, upon the inner edge of the cars 16, provides a means whereby the side walls 13 are held in vertical position, thus the tongues 18 perform the dual function of preventing the inward movement of the end walls 14 and also the outward movement of the side walls 13.

not limited to interlocking the walls of the body of a metal box, but may also be successfully employed in the cover of the box where for some particular reason the lid or cover is of deep construction to accommodate an electrical device having considerable height.

It has been found in practice that the coextending tongues 17 and 19 may be omitted in the construction of the corners and cars 16 of the box when a very heavy gauge metal is used and in their place I propose to set the ear 16 in its proper position by means of an offset caused by striking the surface of the overlapped corner portion with a punch or other suitable means, whereby a dent or inset may be made in the members. This construction is particularly advantageous where very heavy gauge metal is used and it is a simple operation to inset, as shown at 20 in Fig. 5, the adjacent surfaces of the metal ear 16 and wall 13.

The use of knock-out plugs 21 in the walls 13 and 1 of the body portion of the box 10 is known not to be new in the art, but their use in connection with the specific form of box construction herein described is of particular importance because these knock-out plugs may be indicated on the walls 13 and 14 by one operation of the cutting die and at the same time that the tab or tongue 19 is struck out.

1. A folded metal box formed from a cut blank, the body portionof said blank provided with marginal portions adapted to be bent to form the sides of said box, corner ears bent at substantially right angles to each of the edges of alternate side portions, each of said ears having an opening therein, and

. openings therein, It will be understood that the invention is mamas pairs of oppositely extending tongues provided in the other alternate side portions and adapted to interlock with the edges of said ears, one member of each of said pairs of tongues making surface engagement with but not projecting beyond the plane of said ears, and the edges formed by said openings therein whereby each of the sides of said box may be locked in engagement with the adjacent side portion.

2. A folded metal box formed from a cut blank, the body portion of said blank provided with ad acent marginal portions capable of being bent to form side wall members, additional side wall members provided with ears disposed at right angles thereto and adapted to lie parallel to the first mentioned side wall members, an opening formed in the surface of each of said ears, and pairs of oppositely extending tongues provided in the first mentioned side wall members adapted to engage the edges of said ears and the edges formed by said one of said tongues of each pa1r making surface engagement with but not projecting beyond the plane of said ears, whereby the wall members may be held against separation.

3. A folding box made from a cut blank having a bottom provided with marginal portions adapted to be bent to form sides and ends of said box, said ends being provided with ears bent at substantially right angles thereto and having a tongue struck up in each ear, said ears having opposed edges formed by the ends of the ears and the edges formed by cutting out said tongues, and pairs of oppositely extending tongues struck up from the surface of the sides not having said ears, one member of each of said last named tongues making surface engagement with but not projecting beyond the plane of said ears, said last named tongues being further disposed to limit the inward and outward movement of said ends.

4. A folding metal box made from a cut blank having marginal portions adapted to be bent to form the walls of said box, the two alternate walls having ears extendin at substantially right angles thereto an provided with struck up tongues which form an opening and the outer'edge of said ears, and pairs of oppositely arranged tongues struck up from the side walls not having the said ears, said last named tongues being disposed one above the other so that when the side walls having the ears are bent the last named tongues will engage the said opposed exposed edges of the ears, one member of each of said pairs of tongues projecting to but not beyond and those of the openings formed by the tongues in the ears thereby interlocking the walls against relative movement.

expose an edge opposite tothe plane of the adjacent cars 5. A folded metal box formed from a cut blank having marginal portions which are bent at substantially right angles to the portion forming the bottom of said box, ears on two of the marginal bent portions adapted to extend substantially parallel to the adjacent marginal bent portions, each of said ears having an opening therein which presents an edge which is opposite to the outer edge of said ear, and pairs of tongues struck up from the surface of each marginal portion not having said ears, the

free end of said tongues extending substan tially parallel thereto, said tongues extending in opposite directions and arranged one above the other whereby when the marginal portions not having the ears are bent the portions having the ears'may be moved in an arcuate course until the said outer edge of said ear moves under said upper tongue and seats against the rear ofthe latter, one member of each pair of tongues projecting to but not beyond the plane of said ears when they interlock.

6. A metal box, comprising a bottom and side walls, ears projecting from certain of said side walls and lying parallel to the other side walls, and pairs of oppositely pro- .jecting tongues in one side wall engaging an adjacent ear in another side wall, one member of each of said pairs of tongues making surface engagement with but not projecting beyond the plane of said ears.

7. A metal box, comprising a bottom and side walls, a pair of oppositely projecting tongues struck up near the two ends of each of two of said side walls, ears carried at make surface engagement with but not project beyond the plane of said ear In testimony whereof I have aed my signature.

ALBERT n. shalom,

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