US3825355A - Interlocking joint - Google Patents

Abstract

An interlocking joint includes a hollow outer leg having three or more sidewalls which intersect to form at least three vertices, an inner leg member which includes at least three interconnected flanges each of which extend into one of the vertices, and securing means affixed to the inner leg that holds the legs in desired relative position by bearing on one or more sidewalls of the outer leg and thus urges certain of the flanges toward their corresponding vertices.

Description

United States Patent [191 Martin INTERLOCKING JOINT [75] Inventor: Frank Herbert Martin, Holmdel,

[73] Assignee: Bell Telephone Laboratories Incorporated, Murray Hill, NJ.

221 Filed: July 2,1973

21 Appl. No.: 375,613

[52] US. Cl. 403/104 [51] Int. Cl. F16b 1/00 Field of Search 403/298, 52, 109, 104, 403/205, 217, 382, 83; 52/656, 758 H, 475, 285

[56] References Cited UNITED STATES PATENTS 935,592 9/1909 Dougherty 403/104 x 1,625,510 4/1927 Tredwell 403/52 July 23, 1974' 1,830,370 11/1931 Mitchell 403/104 2,304,223 12/1942 Westrope 403/52 3,087,768 4/1963 Anderson et a. 52/758 H Primary Examiner-Richard J. Scanlan, Jr. Attorney, Agent, or Firm-Barry H. Freedman [5 7] ABSTRACT An interlocking joint includes a hollow outer leg having three or more sidewalls which intersect to form at least three vertices, an inner leg member which includes at least three interconnected flanges each of which extend into one of the vertices, and securing means affixed to the inner leg that holds the legs in desired relative position by bearing on one or more sidewalls of the outer leg and thus urges certain of the flanges toward their corresponding vertices.

12 Claims, 16 Drawing Figures PATENTEMmzamu SHEET 2 OF 6 3 N9 wm am c259 Us 5 9w 2m @1 @1 i Q N 6R PAlENTEnJuLzsmu SHEET 0F 6 PATENTEUJUL23I974 FIG/l 3 (E H23 SHEET 5 OF 6 FIG. /4

INTERLOCKING JOINT I BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to an interlocking joint and more particularly to such a joint in which an inner leg member is continuously adjustable in position with respect to an outer leg member, without the need for external locking mechanisms.

2. Description of the Prior Art 1 Numerous ways have been devised to secure an inner leg member within an outer leg member, in a desired contact with the outer member, after the legs are placed in desired position. These arrangements are not always suitable, however, because the pins or bolts detract from the otherwise smooth appearance of the outer legs, and are subject to tampering or other damage because they are at least partiallyextemal to the legs. Also, in some configurations, the leg positions are not continuously adjustable.

Some of the above problems are avoided by another series of prior art patents relating to extensible tele-- scoping legs, which disclose a leaf spring used to urge a locking means attached to the inner leg into engage.- ment with the inner surface of the outer leg. The locking means may be a pivotably attached dog or retainer which acts in a ratchet-like manner. Accordingly, in

certain instances, it is necessary to first'move the legs to an extreme end position in order to disengage the retainer before making a desired adjustment of position. Additionally, this type of mechanism is quite complicated and expensive, and is readily subject to malfunction.

Still another. approach known inthe prior art is'to use a leaf spring with barbs placed in a groove in the outer surface of an inner square leg, which fits within an outer square leg. The spring creates friction between the legs, holding them in desired position; the barbs 2" 4. the locking-means is held in position'by the inner g member.

SUMMARYOF THE INVENTION Each of the foregoing and additional objects are achieved in accordance with the invention by an interlocking joint which broadly includes a hollow outer leg member having a-longitudinal axis and three or more side-walls which intersect to form at least three vertices, an inner leg member which includes at least three interconnected flanges each of which extends into a particular one of the vertices, and securing means atfixed to the inner leg that hold the legs in a'desired relative position by bearing on one or more side walls of the outer leg and thus urges certain of the flanges toward an arcuate spring having at least one simicircular lobe, or a locking pin. In either event, one end of the securing means is affixed to one flange of the inner leg member, and is positioned adjacent .a second'one of the flanges. The radius of the arcuate spring and the length of the locking pin are approximately equal to the discuring means is affixed to the inner legbyextending it through a small hole in the intervening flange.The'

spring is dimensioned as previously indicated so that it assumes a generally circular configuration upon insertion of each semicircle on each flange engaging-or bearing on.a portion of the inner surface of the. outer prevent extraction once the legs are properly positioned. While this arrangement has certain advantages,

it alsohas several drawbacks. Most importantly, since Accordingly, there can be no protrusions into the outer leg which would interfere with the spring. However, these protrusions are necessary if external panels, baffles or other similar items are to be fastened to the outer leg in desired locations. In addition, this approach suffers from the fact that the spring locking means is not secured to the inner leg, thereby subjecting it to misalignment or possible loss.

In view of the foregoing difficulties, it is the broad object of the present invention to provide an improved interlocking joint. Specific objects include a joint design in which:

1. The locking means is simple and inexpensive, and fully contained within the leg members,

2. the leg members are continuously adjustable relative to each other,

3. the locking means does not interfere with protrusions into the outer leg necessary to secure other items thereto, and

leg. This engagement or hearing aforce radially urges certain flanges of the inner leg into contact with vertices of the outer .leg, thereby locking or securing-the legs in a desired relative position. 7 v i In another embodiment, thev outer hollow leg is triangular in shape, and the inner leg iseither T or -Y- shaped in cross section. In the latter instanee, the arcuate spring member is deformed from the previously described planar configuration, so that the semicircles intersect at an acute angle which corresponds to the angle formed by adjacent flanges.

The advantageous design, in accordance with the invention, of an interlocking joint as above described, has

I many advantages. First, since, the locking means in accordance with the invention can be fabricated, for example, from a portion of one convolution of a helical wire spring or from a simple length of wire, it is thus quite simple and inexpensive. Second, by virtue of the fact that the spring is affixed to the inner leg, as for example, by insertion through an aperture therein, .it is held in desired position and cannot be lost or misaligned. While the lockingjmean's is internal to the outer leg, it does not interfere with any protrusions that might be required into that leg, because of theadvantageous use of an inner leg having three or more flanges which contact the outer leg only at its vertices. The leg design in accordance with'the invention also permits continuous adjustment of relative leg positions.

3 BRIEF DESCRIPTION OF THE DRAWING Further advantages and features of this invention will be more readily understood from the following detailed description, when read in light of the accompanying drawing in which:

FIG. 1 is a perspective view of an interlocking joint in accordance with the instant invention, in a disassembled condition;

' FIG. 5 is anend view of the interlocking joint of FIG.

FIG. 6 is a perspective view similar to FIG. 1 showing an interlocking joint with an alternate locking means, in disassembled condition;

FIG. 7 is a partially cut-away front view of the jointof FIG) 6 in which the leg members are fully assembled;

FIG. 8 is an end view of the interlocking joint of. FIG. 7; f

FIG. 9 is a perspective view of another embodiment of an interlocking joint in accordance with the invention;

' FIG.= 10- isan end view of the joint of FIG. 9;

FIGS. 1 115 are end views of other configurations of interlocking joints in accordance with the invention; and a FIG. 16is a perspectiveview of a cubicle fabricated using-a number of interlocking joints in accordance with the invention, with insets showing portions of the joints in detail.

DETAILED DESCRIPTION- Details of the invention will best be understood by first considering one embodiment thereof, depicted in various views and conditions in FIGS. 1-5, in which the same numerals are used to indicate similar parts. FIG. 1 shows an interlocking joint in accordance with the invention which includes anouter leg member 10, an inner leg member 20, and a locking or securingmeans. Leg 10 is an elongated hollow tube having a square cross section. As shown in the end view of FIG. 5, leg 10 includes four sidewalls 11, 12, 13 and 14 which intersect to form four vertices l5, l6, 17-and 18. Leg 20, which is adapted for longitudinal insertion into leg 10, includes four interconnected flanges 21, 22, 23 and 24 which form an X or cruxiform shape in cross section. The extremities 25, 26, 27 and 28 of each flange, i.e., the furthermost portion of each flange from the intersection of that flange with the remainder of flanges of leg 20, are dimensional so as to extend and fit into a vertex of leg 10. Thus, extremity 25 of flange 21 extends into vertex 15, extremity 26 of flange 22 extends into vertex l6, and so on. To enable a closer fit, extremities 25, 26, 27 and 28 may be chamfered or tapered, if desired. The securing means, shown in FIGS. l-S is an arcuate spring member 30 including a pair of generally semicircular lobes 31 and 32.. One end 31a,

32a of each lobe may be affixed to one flange (flange,

24 shown) of leg at a point somewhat removed from the extremity 28 of the flange by welding or other suit- 4 able fastening means. Alternatively, as shown in the drawing, member 30 may be fabricated from a portion of one convolution of an ordinary helical wire spring.

In this event, member 30 can be affixed to leg 20, i.e., maintained in a desired position with respect to leg 20, simply by forming an aperture 40 in flange .24 and by passing spring member 30 about halfway through the aperture. The radius of lobes 31 and 32 is chosen to be approximately equal to the distance between the point of affixation (aperture 40, for example) and the extrernity of the flange adjacent which the lobe is positioned. Thus, more specifically, lobe 31, which is positioned adjacent flange 21, has a radius equal to the distance' between aperture 40 and extremity lobe32, which is positioned adjacent flange 23, has a radius equal to the distance between aperture 40 and extremity 27, which in this case is the same as the radius of lobe 31. The length of each lobe, while approximately semicircular, isnot critical. As will be seen hereinafter, the length canvary by an amount equal to the width of the flange 24 which intervenes between the flanges 21, 23 on which the spring member is positioned, o r sometimes even more, without affecting satisfactory operation of the invention.

- Operation of the interlocking joint of FIG. 1 will best be understood by reference to FIGS. 2-4, which illustrate the relative positions assumed by the parts of the joint as leg 20 is inserted into leg 10. In FIG. 2, spring member 30 has not yet engaged the sidewalls of outer leg 10. Accordingly, depending on the size of member 30, there may be a small degree of clearance between the free ends 31b, 32b of lobes 31 and 32 and flange 24. In FIG. 3, spring member 30 has partially engaged the sidewalls of outer leg 10, as the inner leg is longitudinally inserted therein. At thispoint, the free ends 31b and 32b of lobes 31 and 32 make conta'ct withv flange 24, and the force required for continued insertion substantially increases. This force persists as leg'20 is further inserted in leg 10 so as to fully enclose spring member 30, as shown in FIG. 4. In this position, portions 31c and 3200f lobes 31 and 32 bear on the interior of sidewalls 11 and 12 of leg 10. This'bearing' or force urges leg 20 in a direction transverse to its longitudinal axis, as shown in the end view of FIG. 5, since member 30 seeks" to expand into the widerportion of leg 10 that is occupied by flanges 21 and 23. Thus, flange 26 is urged toward vertex 16 of leg 10. In addition, portions of flanges 21 and 23 are urged toward sidewalls 14 and 13 of leg 10 in the vicinity of vertices 15 and 17, respectively. For purposes of illustration,

the points of contact are designated 50, 51, 52 and 53,.

it being understood that in reality flanges 21 and 23 as well as flange 22 engage the corresponding vertices on longitudinal lines which pass through points 50, 51, 52

and 53. By virtue of the aforedescribed action, inner leg 20 is held in a desired relative position with respect to outer leg'10. The relative positions of the legs may be changed when desired, but the friction forces between flanges 21, 22 and 23 and vertices 15, 16 and 17 must of course be overcome. By way of example only, for an interlocking joint construction of extruded aluminum the force typically required to overcome friction is on the order of 50 pounds. Of course, the friction forces generated in a particular embodiment depend upon the diameter of spring member 30, and the material from which it and outer leg 10 are con structed.

As mentioned previously, the length of lobes 31 and 32 of spring member 30 may be increased beyond a semi-circular shape without interfering with proper joint operation. In this event, when leg 20 is inserted within leg 10, the free ends 31b and 32b of each spring lobe simply spread in a longitudinal direction and contact the sides of flange 24 at points further removed from points of affixation 31a and 32a. Also, lobes 31 and 32 become somewhat deformed, each assuming an approximately half-oval shape. However, the holding force between legs and 20 remains adequate, and can even increase.

It is important to note several minor modifications or adaptations that can be made to the interlocking joint arrangement of FIGS. l-S. First, it should be understood that the free ends 31b, 32b of lobes 31 and 32' may be located either forward or rearward of the fixed ends of the lobes, forward being defined as the direction toward which leg 20 is moved when being inserted in leg 10. Second, it should be apparent that more than one spring member such as member 30 may be used,

especially where the assembled joint is relatively long, e.g., longer than 2 or 3 feet. If multiple securing means are used, they need not be affixed to the same flange. Third, where a single spring member is utilized, it can be affixed to leg 20 at various points along the legs length, but is advantageously centrally located, so that the holding force is more uniformly distributed.

As shown in FIG. 6, another form of locking or securing means that can be used in lieu of or in addition to spring member 30 is a locking pin 60 affixed to one flange 24 of leg 20 and positioned adjacent to at least another one of the flanges (e.g., flanges 21 and 23). As with spring member 30, affixation of pin 60 may be accomplished by welding or any other suitable technique, or a single pin having two arms 61 and 62 may be inserted through an aperture 40a in the flange 24 intervening flanges 21 and 23 upon which the pin is positioned. The length of each pin arm 61 and 62 is chosen to be approximately equal to the'distance between the point of affixation (e.g., aperture 40a) and the extremity 25, 27 of the flange on which the pin is positioned.

When inner leg 20 is inserted into outer leg 10, as shown in FIG. 7, arms 61 and 62 are bent rearwardly as their free ends 61a and 62a engage sidewalls 11 and 12, respectively. In a manner analogous to the operation of spring member 30, the free ends 61a and 62a bear on the sidewalls and urge flange 22 toward vertex 16. In addition, as explained previously, portions of flange 21 and 23 are urged toward sidewalls 14 and 13 of leg 10 in the vicinity of vertices 15 and 17, respectively. Thus, leg is held securely'in a desired relative position with respect to leg 10, by the friction forces between flanges 21, 22 and 23 and vertices 15, 16 and 17 as previously described, and as further shown in FIG. 8. However, there is one important difference between locking pin 60 and spring member 30: the free ends 61a and 62a of arms 61 and 62 of locking pin 60, when rearwardly bent, act to grip side-walls 11 and 12 and prevent subsequent extraction of inner leg 20 from outer leg 10. This one-way action of the arms of pin 60 results from the fact that free ends 160 and 62a can slip over the inner surfaces of leg 10 during insertion, but are forced or jammed into the inner surfaces when extraction is attempted. Insummary, locking pin 60 serves two purposes. During insertion or forward movement, it'bears on the sidewalls of outer leg 10 and urges one or more flanges ofinner leg 20 into frictional engagement with corresponding vertices; when rearward movement is attempted, its free ends act to engage the sidewalls of leg 10. much like a pawl engages a ratchet, and prevents extraction. By way of example, the force required for insertion compared to the extraction force needed to break pin 60 can easily be on the order of 1 to 20.

Referring now to FIGS. 9 and 10, there are shown perspective and end views, respectively, of anotherembodiment of the instant invention. In this arrangement, an interlocking joint includes a tubular hollow outer leg having a triangular cross-section, and an inner leg adapted for longitudinal insertion therein. Inner leg 100 comprises three interconnected flanges 101,

102 and 103 which form a Y-shaped cross-section. Each of the flanges fits within one of the vertices 91, 92 and 93 of outer leg 90. In this embodiment, a securing means 110 similar to spring member 30 may be affixed to one flange, e.g., flange 101, and be positioned on adjacent flanges 102 and 103. Affixation may be accom-,

plished by inserting securing means 110 through an aperture 120 formed in flange 101, and the dimensions of securing'means 110 determined. as set out above. As in the afor edescribed embodiment, securing means 110 acts to bear on sidewalls 94 and 95 of outer leg 90, and thereby urge the extremities and 106 of flanges 102 and 103 into engagement with vertices 92 and 93, respectively. Thus, when inserted, leg 100 is held in a desired relative position with respect to leg 90, as shown clearly in FIG. 10.

Although securing means 110 is similar to spring member 30, it is not identical thereto. Securing means 110 is nonplanar, its'lobes 111, 112 defining planes which intersect at an angle 0 which corresponds to-the angle formed by flanges 102 and 103. As an alternative, securing means 110 can be supplemented orv replaced by a locking pin, not shown, similar to locking pin 60. However, such a locking pin, if fabricated froma length of wire having two arms inserted through aperture 120, must be V-shaped at an angle 0, so that the arms can assume positions adjacent to flanges 102 and 103.

Numerous other configurations of elongated inner and tubular hollow outer leg members may also be practiced in accordance with the instant invention. Each of these arrangements, which are shown in end view in FIGS. 11 through 15, may use securing means similar to spring member 30 or locking pin 60.

In FIG. 11, the outer leg 1,110 is rectangular in crosssection. The inner leg 1,120 includes three interconnected flanges 1,121, 1,122 and 1,123 having a T- shaped cross-section each of which extend into a vertex of the outer leg, and a fourth flange 1,124 the extremity of which need not contact outer leg 1,110. Flange 1,124 serves only as a location for affixing securing means 1,130; this flange need not run the entire length of inner leg 1,120, but may instead include one or more flange-like tabs which hold the securing means in a desired position. In operation, this configuration is identical to the one of FIGS, 1-8. Thus, securing means 1,130 bears'on the sidewalls of outer leg 1,110, and urge flanges 1,12l, 1,122 and 1,123 into or toward their corresponding vertices.

In FIG. 12, the outer leg 1,210 is again rectangular.

each of which extend into a vertex of the outer leg. One

? offset from the remaining diagonal, their intersections with the first pair of flanges being at different points. In this configuration, securing means 1,230, similar to spring member 30, includes two generally semicircular lobes 1,231, 1,232 which have different radii. The radius of lobe 1,231 is approximately equal to the distance between the point of affixation 1,233 to one side of flange 1,221 and the extremity of flange 1,224, and the radius of lobe 1,232 is approximately equal to the distance between the point of affixation 1,234 to the other side of flange 1,221 and the extremity of flange 1,223. Alternatively, if a two armed locking pin similar to locking pin 60 is used, the arms would be of unequal lengths. In either event, the securing means may be affixed to fl ange 1,221 by insertion through an aperture therein, and serves to bear on the sidewalls of outer leg 1,210 and urge flanges 1,222, 1,223 and 1,224 into engagement with their corresponding vertices.

Still other configurations are illustrated in FIGS. 13-15. The operation of each arrangement is similar to that of the aforedescribed embodiments, and will not be described in detail. Suffice it to say that in the joint of FIG. 13, the outer leg 1,310 is five sided, while the outer legs 1,410 and 1,510 in FIGS. 14 and 15 are hexagonal; In the arrangement of FIG. 13, the inner leg 1,320 is generally T-shaped in cross-section, while inner legs 1,420 of FIG. 14 and 1,520 of FIG. 15 are similar to'the inner legs shown in FIGS. 12 and 5, respectively. The securing means 1,330, 1,430 and 1,530 in each arrangement may be similar to spring member 30 or locking pin 60. Many other arrangements with different inner and outer leg configurations can also operate satisfactorily, as will be evident to those skilled in the art.

Although there are many varied uses for the interlocking joint of the present invention, it will be instructive to describe one particular applicationin the field of cubicle fabrication. FIG. 16 illustrates one such cubicle," known in the telephone industry as a position, which partitions floor space into a small office or complex of offices in which employees such as opera tors may "perform their assigned tasks without interrupting or being interrupted by personnel working in adjacent areas. The position may include a series of baffles or walls 1,601, 1,602 and 1,603 which partially surround the working area, and one or more tables or shelves 1,610, 1,611 which are mounted on the walls. To give a modern and airy appearance, the walls may include translucent panels 1,604, 1,605 affixed to the upper portions of the walls.

Several interlocking joints in accordance with the instant invention are used in constructing the position of FIG. 16. For example, vertical leg 1,620 is connected to bat'fle brace leg 1,630 by a two-way corner assembly 1,640. Legs 1,620 and 1,630 are similar to outer leg 10 of FIG. 1. Corner assembly 1,640 comprises two leg members 1,641 and 1,642 similar to inner leg 20 of FIG. 1, connected at right angles to each other by a hub 1,643. Affixed to legs 1,641 and 1,642 are securing means 1,644, 1,645, respectively, which may be similar to spring member of FIG. 1. Leg members 1,641 and 1,642 areinserted within legs 1,620 and 1,630, respectively, and are held in desired position by the securing means, as previously explained. U-shaped channels 8 1,621, 1,631 maybe connected to one outerwall of legs 1,620 and 1,630, so as to hold panel 1,604 in place.

Channels 1,621 and 1,631 can be attached to their re- 'with the invention. v In a similar manner, 'baffle brace leg 1,630 is connected to battle brace leg 1,660 and vertical leg 1,670 by a three way corner assembly 1,680. The latter includes three leg members 1,681, 1,682 and 1,683 similar to inner leg 20 of FIG. 1,connected at right angles to each other at hub 1,684. Each leg includes a corresponding securing means 1,691, 1,692 and 1,693.

From the above examples, it will be evident that various combinations of interlocking joints in accordance with the invention can be combined to allow interconnection at mutually right angles of up to six outer legs at a single hub. These legs can be used for numerous purposes. It is also to be noted that a cap member, 1,650 which is simply a one-way hub, can be inserted in a leg such as leg 1,651 to provide the latter with a smooth, finished looking exterior. In this case, it is advisable to employ a securing means 1,652 similar to locking pin of FIG. 6, so that once the cap member is positioned, it-cannot thereafter be extracted. It will be apparent from the foregoing that one skilled in the art may make various changes and modifications to the apparatus disclosed herein without departing from the spirit and scope of this invention, which is defined in the appended'claims. I

What is claimed is: 1. An interlocking joint including 1 an outer leg member comprising a hollow elongated tube having a longitudinal axis and at least three side walls, said side walls intersecting to form at least three vertices, g

an inner leg rnember adapted for longitudinal insertion into said outer leg, said inner leg member comprising at least three interconnected flanges each having an extremity extending into a particular one of said vertices, and

securing means affixed at a point to a first one of said flanges arranged to bear on the interior of at least one of said side walls of said outer leg member, so as to urge at least a second one of said flanges of said inner leg member toward the corresponding one of said vertices,

thereby securing said inner leg member in a desired relative position with respect to said outer leg member.

2. The invention defined in claim 1 wherein said securing means includes an-arcuate spring member having at least one semicircular lobe positioned adjacent another one of said flanges and having a radius approximately equal to the distance between said point of affixation and said extremity of said other flange.

3. The invention defined in claim 1- wherein said securing means includes a locking pin positioned adjacent another. one of said flanges and having a length approximately equal to the distance between said pointof affixation and said extremity of said other flange.

4. The invention defined in claim 1 wherein said outer leg member is rectangular in cross section,

said securing means includes an arcuate spring member having two semicircular lobes each positioned on opposite flanges of said inner leg member, said spring member having a radius approximately equal to the distance between said point of affixation and said extremity of one of said opposite flanges, and

said first one of said flanges intervenes between said opposite flanges.

5. The invention defined in claim 4 wherein said first one of said flanges includes an aperture formed therein and said spring member is affixed to said first one of said flanges by insertion through said aperture.

6. The invention defined in claim 1 wherein said outer leg member is triangular in cross section and said inner leg member is Y-shaped in cross section.

7. An interlocking joint comprising a tubular hollow outer leg having an interior surface, an inner leg having at least first, second and third interconnected flanges adapted for longitudinal insertion in said outer leg, and

securing means affixed to said inner leg for maintaining said inner leg in a desired position with respect to said outer leg by urging ones of said flanges toward said interior surface.

8. The invention of claim 7 wherein said securing means includes an arcuate spring member having at least one generally semicircular lobe affixed to said first flange and positioned adjacent said second flange.

9. The invention defined in claim 7 wherein said first flange includes an aperture formed therein, said securing means includes an arcuate spring member having two generally semicircular lobes, and

said spring member is affixed to said first flange by insertion through said aperture.

10. The invention defined in claim 7 wherein said securing means includes a locking pin affixed to said first flange and positioned adjacent to said second flange, the length of said pin being approximately equal to the width of said second flange.

11. In an interlocking joint comprising a first rectangular hollow leg, a second X-shaped leg including four mutually perpendicular flanges, said second leg adapted for longitudinal insertion in said first leg whereby opposite pairs of said flanges are positioned along the cross sectional diagonals of said first leg, means for securing said second leg in said first leg, said securing means including an arcuate spring member positioned on one planar surface formed by one of said pairs of opposite flanges and affixed to the one of said flanges intervening said pair of opposite flanges.

12. The invention defined in claim 11 wherein said intervening flange includes an aperture formed therein and said spring member is inserted in said aperture. I

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION- Patent No. 3,825,355 Dated July 23, 197

Inventor(s) Eran}; H Martin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

A line has been omitted aftef "toward" on line 15, after "toward" add:

--their corresponding vertices. The securing means can be-. 7 ,e-

Column 5, line 63, "16a" should read --61a Signed and sealed this 19th day of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents po'wso Y 1 I USCOMM-DC scan-Pea i ".5. GOVIRMIINT PRINTING OFFICI "I! 0-Sli-3S4.

Claims (12)

1. An interlocking joint including an outer leg member comprising a hollow elongated tube having a longitudinal axis and at least three side walls, said side walls intersecting to form at least three vertices, an inner leg member adapted for longitudinal insertion into said outer leg, said inner leg member comprising at least three interconnected flanges each having an extremity extending into a particular one of said vertices, and securing means affixed at a point to a first one of said flanges arranged to bear on the interior of at least one of said side walls of said outer leg member, so as to urge at least a second one of said flanges of said inner leg member toward the corresponding one of said vertices, thereby securing said inner leg member in a desired relative position with respect to said outer leg member.

2. The invention defined in claim 1 wherein said securing means includes an arcuate spring member having at least one semicircular lobe positioned adjacent another one of said flanges and having a radius approximately equal to the distance between said point of affixation and said extremity of said other flange.

3. The invention defined in claim 1 wherein said securing means includes a locking pin positioned adjacent another one of said flanges and having a length approximately equal to the distance between said point of affixation and said extremity of said other flange.

4. The invention defined in claim 1 wherein said outer leg member is rectangular in cross section, said inner leg member is X-shaped in cross section, said securing means includes an arcuate spring member having two semicircular lobes each positioned on opposite flanges of said inner leg member, said spring member having a radius approximately equal to the distance between said point of affixation and said extremity of one of said opposite flanges, and said first one of said flanges intervenes between said opposite flanges.

5. The invention defined in claim 4 wherein said first one of said flanges includes an aperture formed therein and said spring member is affixed to said first one of said flanges by insertion through said aperture.

6. The invention defined in claim 1 wherein said outer leg member is triangular in cross section and said inner leg member is Y-shaped in cross section.

7. An interlocking joint comprising a tubular hollow outer leg having an interior surface, an inner leg having at least first, second and third interconnected flanges adapted for longitudinal insertion in said outer leg, and securing means affixed to said inner leg for maintaining said inner leg in a desired position with respect to said outer leg by urging ones of said flanges toward said interior surface.

8. The invention of claim 7 wherein said securing means includes an arcuate spring member having at least one generally semicircular lobe affixed to said first flange and positioned adjacent said second flange.

9. The invention defined in claim 7 wherein said first flange includes an aperture formed therein, said securing means includes an arcuate spring member having two generally semicircular lobes, and said spring member is affixed to said first flange by insertion through said aperture.

10. The invention defined in claim 7 wherein said securing means includes a locking pin affixed to said first flange and positioned adjacent to said second flange, the length of said pin being approximately equal to the width of said second flange.

11. In an interlocking joint comprising a first rectangular hollow leg, a second X-shaped leg including four mutually perpendicular flanges, said second leg adapted for longitudinal insertion in said first leg whereby opposite pairs of said flanges are positioned along the cross sectional diagonals of said first leg, means for securing said second leg in said first leg, said securing means including an arcuate spring member positioned on one planar surface formed by one of said pairs of opposite flanges and affixed to the one of said flanges intervening said pair of opposite flanges.

12. The invention defined in claim 11 wherein said intervening flange includes an aperture formed therein and said spring member is inserted in said aperture.

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