US2835513A - Means for angularly joining rigid metal tubing including a flat key element - Google Patents

Description

MEANS FOR ANGU OINING RI ME TUBING y 1958 w. s. PEARSO 2,835,513

LARLY J INCLUDING A FLAT KEY MEN Filed Dec. l5, 19

F 4 [-711 TATFF' 10 51 572223? W1! [jam 5. Pearson MEANs FOR ANGULARLY JOINING RIGID METAL TUBING INCLUDING A FLAT KEY ELEMENT William S. Pearson, Baltimore, Md. Application December 13, 1954, Serial No. 474,699

2 Claims. (Cl. 285-222) The present invention relates to a new and improved means for angularly joining rigid, hollowmetal tubing members wherein an end portion of one of the hollow tubes is deformed into tight locking engagement within the interior of another hollow tube.

In accordance with the general features of the instant invention, means are provided whereby the end portion of a first rigid hollow metal tube is disposed angularly within the axial bore of a second tube and the tubes locked together by expansively deforming the end portion of the first tube into tight locking engagement with the interior of the second.

A principal feature of this invention lies in the provision of means for expansively deforming the end portion of a-tube disposed angularly within the axial bore of another, such means comprising a novel key carried by the end portion of the former tube and which responds to and reacts to axial pressure applied to the tube upon which the key is carried by expansively deforming the end portion of the tube into tight locking engagement with the interior of another tube.

It is, therefore, an object of this invention to provide a means for angularly joining rigid, hollow metal tubes.

Another object is the provision of a novel key which allows the end portion of one rigid, hollow metal tube to be expansively defonned into tight locking engagement with the interior of another tube.

A further object is the provision of a hollow, rigid metal tubing construction in which one tube is held in locked angular engagement with another tube by expansively deforming an end portion of the former into tight locking engagement with the interior of the latter.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying sheet of drawings, in which:

Figure 1 is a fragmentary elevational view of a pair of hollow, rigid metal tubes angularly joined in accordance with the instant invention; 7

Figure 2 is a perspective view of one embodiment of the novel tube expanding key employed in the instant invention;

Figure 3 is a fragmentary, longitudinal sectional view with parts in elevation and parts in section illustrating the manner in which the key shown in Figure 2 is employed in joining tubes together;

Figure 4 is a fragmentary sectional view with parts in section and parts in elevation taken through the union of two metal tubes joined in accordance with the instant invention;

Figure 5 is a view taken substantially along the section line VV of Figure 4; and

Figure. 6 is a perspective view of another embodiment of a novel tube expanding key which may be employed in the instant invention.

By way of illustration, the instant invention is illustrated in the drawings in conjunction with the joining or union of two, hollow, rigid, metal tubes 10 and 11, respectively.

The tube 10, which is illustrated as having a substantially larger diameter than the tube 11, has an axial bore 12 defined by a cylindrical wall 13. The smaller diametered tube 11, likewise, has an axial bore 14 defined by a cylindrical wall 15.

Tube expanding and deforming means are provided 'for tightly locking the end portion of the tube 11 within the interior of the tube 10. Such means (Figure 2) include a generally paddle-shaped tube expanding key 16 adapted to be carried within the axial bore 14 of the tube 11 in an end portion thereof. To this end, the key 16 has a generally rectangular first part 17 which is dimensioned for snug slidable engagement within the bore 14, and a generallyrectangular, integral, larger second portion 18 merging with the first part 17 in tapered relation thereto at shoulders 19 on the sides of the key. The corners of the smaller first part 17 and the larger second part 18, are rounded or chamfered. This aids in introducing the first part 17 into the axial bore of the tube 11 and the second larger part 18 intoa suitable aperture formed in the wall of the tube 10.

The smaller, first part 17 of the key 16 is preferably transverselydimensioned to have a width substantially equal to or just slightly smaller than the diameter of the axial bore 14 of the tube 11. To aid in retaining the key 16 inthe end portion of the tube 11 during joining thereof with the tube 10, the width of the first part 17 is preferably such that the first part is slidably receivable snugly within the axial bore 14 of the tube 11.

The width of the larger sectiond portion 18 is greater than the width of the first part 17, and preferably is transversely dimensioned to have a width substantially the equivalent of the outer diameter of the tube 11.

The length of the second part 18 of the key 16 may be substantially equal to or slightly smaller than the diameter of the axial bore 12 in the tube 10. Preferably, however, the second part 18 is longitudinally dimensioned to have a length substantially equal to the diameter of the axial bore 12 minus the thickness of the wall 15 of the tube 11. This insures a tight fit between the outer periphery of the tube 11 and the margin of an aperture 20 provided in the wall of the tube 10 in which the tube 11 is inserted when the end portion thereof is expanded into tight engagement With the interior of the tube 10.

The key 16 may be formed from a suitable strip or sheet metal stock, such as by die punching or the like, and preferably having a sufiicient hardness and resistance'to bending and compressive deformation to allow expansive tube wall deformation or displacement thereabout without being deformed itself.

In joining the tubes 10 and 11 together in a tight angular relationship, the aperture 20 is first formed in the cylindrical wall 13 of the tube 10 (Figure 3). The aperture 20 preferably has a diameter substantially equal to the outer diameter of the tube 11 so that the tube 11 may be inserted therein and have a snug sliding fit with that part of the Wall 13 defining the margin of the aperture 20.

The key 16 is disposed to be carried by the end portion of the tube 11 by slidingly introducing the first, smaller width part 17 of the key 16 into the axial bore 14 of the tube 11. When thus positioned, the key 16 rests on the marginal extremity of the tube 11 on the tapered shoulders 19 with the larger width second part 18 of the key projecting axially beyond the extremity of the tube 11.

on or butted against the inner surface of the wall 13 in axially to the tube 11 radially inwardly toward the tube 10 while solidly backing the wall of the latter exteriorly opposite the end of the key 16. As the assembly pressure is applied the second part 18 of the key 16 in cooperation with the tapered shoulders 19 functions in a wedge-like manner, allowing the inwardly moving tube wall 15 to be expansively displaced or deformed over and'about the side edges of the second part 18. To this end, the shoulders 19 provide means for guiding the expansive deforming displacing movement of the end portion 11a of the tube wall over and about the, larger key part 18. As a result diametrically opposed locking means in the form of ribs 21 (Figs. 4 and are formed on the end portion 1111 within the tube 10. These ribs 21 expand the inserted tube portion 11a to an over-all larger dimension than the aperture 20 and thus prevent withdrawal of the tube 11 from the assembled relation. In the region of the tapered shoulders 19 there is provided by the outer ends of the ribs 21 a tight gripping, interlocking engagement with the marginal portion of the aperture 20 to effectively prevent rotation of the tube 11. Rotation is further prevented by the fact that as ribs are deformed or displaced outwardly as seen from the side in Figure 4, other parts of the end portion are deformed or displaced inwardly as shown from the top at 22 in Figure 5. This deformation produces an outof-round configuration at the end of tube 11 which coacts with the inner bore 12 of tube to lockingly prevent relative rotation of the tubes.

Additional locking of the tube 11 against rotation relative to the tube 10 attains as a result of drawing in of the extremity of the tube terminal portion 11a, as seen at 22 in Figure 5, toward the extremity of the key part 18, thus generally flattening the tube terminal parallel to the axis of the tube 10. Interengagement of the tips of the flattened sides 22 with the cylindrical bore 12 cooperates with the shoulder interlock to resist relative turning as well as relative canting.

In Figure 6 is shown another embodiment of a tube displacing key which may be employed in the instant.

method. As seen therein this key 23 includes a first part 24 adapted to be received within the axial bore of the tube 11 in the same fashion as the first part 17 of the key 16. The key 23 also includes a second integral portion 25 adapted to project axially from the end portion of a tube in which the key 23 is carried The second portion 25 merges with the first part 24 at a pair of laterally opposite lug portions 26 formed on the side of the key 23.

The width of the key 23 in the region of the lugs 26 is preferably substantially equal to the outer diameter of the tube 11; the lugs 26 acting in substantially the same wedge-like manner in guiding and effecting tube displace ment as the shoulders 19 on the key 16.

The key 23 may be cut from suitable strip metal stock and the lugs 26 formed thereon by upsetting the edge portions of the key by suitable punch or die means.

It will be appreciated that the instant invention provides an economical, efiicient method whereby a pair of hollow substantially rigid metal tubes can be joined angularly in an improved manner. No external fastening means are exposed to the exterior of the tube union and, accordingly, the aesthetic qualities of the instant tube joint are superior to those obtainable by the use of rivets, brazing, welding or the like.

In addition, by expansively deforming the end portion of one tube into tight locking engagement with the interior portion of another, large tube areas are contacted in locking relation making for a tighter and stronger union than is possible with rivets or similar external fastening devices. Further it is not necessary to provide slots or holes through the tubes, such as is required in employing rivets or the like. This absence of apertures other than the aperture 20 formed in the tube 10 to receive the tube 11, minimizes the possibility of ingress of water within the tube construction and provides a more weather resistant joint.

Although the instant invention is applicable for angularly joining substantially all forms of rigid metal tubing, it is especially suitable for producing ladders, play ground equipment, fences and scaffolds, besides many other uses.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a rigid hollow tubing construction including a first tube having an aperture formed in the wall thereof for receiving a second tube the improvement comprising, a key including a first part adapted to be carried by the axial bore of the second tube in an end portion thereof, and an integral larger substantially flat second part, said second part having a length slightly less than the inside diameter of the second tube, and an end remote from said first part defining a line transverse to the axis of said tube end portion, said second part adapted to project axially therefrom for joint disposition with said end portion via said aperture within the axial bore in the first tube with the end of said second part engaging the interior of said second tube along an axial line, said key parts being smoothly joined by a shoulder portion providing a camming surface adapted to react therein to axial pressure applied relative to said end portion radially inwardly toward the first tube to eifect and guide an out-of-round expansive tube deformation of said end portion by said surface as said second tube is forced over said surface during movement of the said second tube past said surface to lock the tubes tightly against disengagement and relative rotation.

2. In a rigid hollow tubing construction, the combination of: a first tube having an aperture in the wall thereof; a second tube having an out-of-round end portion extending inwardly of said aperture; and a key including a first part thereof carried by the axial bore of said second tube adjacent to said out-of-round end portion, and an integral substantially flat second part disposed within said end portion; said second part having a length slightly less than the inside diameter of said first tube and a width slightly less than the diameter of said aperture, and an end remote from said first part engaging the interior of said first tube along an axial line, said key parts being smoothly joined by a shoulder portion disposed slightly inward of said aperture; said out-of-round end portion having a transverse dimension slightly greater than said aperture and snugly disposed intermediate said shoulder portion and said aperture, whereby said tubes are positively locked against disengagement and relative rotation.

References Cited in the file of this patent UNITED STATES PATENTS 1,010,427 Holden Dec. 5, 1911 1,521,805 Ellis Jan. 6, 1925 1,989,955 Van Patten Feb. 5, 1935 2,140,919 Mushet Dec. 20, 1938 2,415,232 Brock Feb. 4, 1947 2,614,827 Peach Oct. 21, 1952 FOREIGN PATENTS 826,246 Germany Nov. 22, 1951 133 Great Britain Jan. 19, 1954

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