US1880479A - Airplane truss joint construction - Google Patents

Description

1932- E. J. w. RAGSDALE 1,880,479

AIRPLANE TRUSS JOINT CONSTRUCTION Filed July 16, 1929 IN V EN TOR.

EARL lW. RAGSDALE mean Oct. 4, 1932 v UNITED STATES PATENT OFFICE EARL J'. W. RAGSIJALE, OF NOBBIS'IOWN, PENNSYLVANIA, ASSIGNOB T EDWARD G. BUDD MANUFACTURING 00., OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION or PENNSYLVANIA AIRPLANE TBUSS JOINT CONSTRUCTION Application filed July 16, 1929. Serial No. 878,614.

at the joints, then beading the members at the joint, beading those integrally joined angularly related structural members of the web around the angle-itself, gradually washing out the head from the apex of the angle.

- In constructing these members of high grade steel of a tensile strength approaching two hundred thousand pounds per square inch, these beads have been found very diflicult to draw. The objects of the method of my in- 4 vention are not only to produce economical and efiicient joints but also the most perfect joint from the standpoints of most eflicient distribution of material, strength, and neatness in appearance, and to eliminate abso-- lutely all irregularities which might under the strains of usage give rise to faults.

I utilize channel stock in the main though I may use other forms of angle or open sec-' tion stock. I bend this stock to form the .angles between the continuous integrally connected structural members. At the time of bending I flatten the stock extending around the angles and form a flattened apex of the angle. Thereupon I bead the stock interiorly of the-angle, bead it deepest in the flattened apex and the immediate adjoining side walls and then gradually taper the bead until it vanishes in the recession of the structural member from the apex. I draw this head on a line in general bisecting the angle between the structural member and pocket the draw in its general main direction and on opposite sides of the apex in such manner that the metal of the bead on the sides of the angle is first drawn and thereafter the metal of the apex, and in such manner further that the" metal of the sides of the angle is in general displaced substantially along the structural members themselves and away from the apex. Thereby I prevent wrinkles and cracks in steel of high tensile strength.

Figure 1 is a side elevation of the airplane rib in which the making of my inventlon is used, and

Figure 2 is an enlarged section in the plane of the rib of a joint in which the method of my invention has been fully employed.

Figure 3 is a side elevation of the same.

Figs. 4 and 5 are perspective views showing channel flattening steps for forming one form of the structural'member.

Figures 6 and 7 show thebeading operation performed upon a second form of the structural member the dies being shown in section in the plane of the rib.

Figures 8 and 9 are details of the nose and tail of the rib. respectively.

10 are the chord. members continuous themselves, 11 are the web members also of continuous strip stock bent in zigzag fashion to contact at the apexes of the zigzag with the chord members.

In the bending of these web members it will be noted they are of channel section, v

the apices of the angles are flattened, the side walls of the channel section being bent progressively outward as they approach the apex of the angle to the full flat of the apex. This is done as shown in Figs. 3 and 4, first the flat being formed as in Fig. 3, then the bend to form the apex of members 11 as in Fig. 4. They are then subjected to a die drawing operation to form a head 12 ex tending around the angle interiorly thereof. This beading is stepped or pocketed on opposite sides of the angle and is drawn as shown in Figs. 5, 6 and 7 by first efi'ecting drawing engagement on opposite sides of the angle as commenced in Fig. 6, and before the apex is subjected to drawing engagement. This draws metal away from the apex. Yet further, this pocketed drawing of the sides of the angle carries the metal along the sides as indicated by the arrow in Figs. 6 and 7 and in general away from the apex. The ensuing and ultimate concurrent engagement bead at the apex without crowding of the 1 'metal at the apex, and free from wrinkles and folds and cracks or any other irregularities which detract from appearance or from the strength or which may ultimately develop faults in use. Moreover, through the pocketing of the draw, I find it feasible to most eificiently distribute the metal of the bead to obtain maximum stiifening of the joint.

. This I do by appropriate relative depths.

The general line of the draw being along the line 14 which bisects the angle between the structural members, it may be said that the stepping or pocketing is in the same di rection and that the flow of metal along the structural members in the direction shown by the arrows is as a result of strong components of applied force on opposite sides of the angle in the general direction of the draw.

t is especially to be noted that the bead 12 at its apex 15, as shown in Figure 2, does not touch the complemental bead 16 of the chords 10. This is in order to make sure that the flattened portions 1718-do touch each other as clearly appears, particularly Fig. 3, but also in Fig. 2 and that they can therefore be the more certainly and perfectly welded together.

It is to be further noted that in the drawing operation of Fig. 7 beads 12 touch the bottom of groove 19 in the lower die 20 only at the apex 15. Elsewhere in its side portions it is spaced from the bottom of groove 19 and the stepped drawing operation is performed through appropriate configuration of the upper. die 21. In other words, the grooves 19 of the lower die are of uniform depth and width, while the forming portion of the upper die 21 is of varying depth according to the degree of pocketlng desired in connectionwith the bead 12.

The truss of Figure 1 has the form'of an aeroplane rib. Extended flattened portions 22 and 23 between the trussing 11 provide seats for front and rear beams 2425 indicated in dotted lines. The flattened portions are formed merely by outturning a greater length of the side portions of the chords 10 and the trussing 11 in the same manner as are formed the flattened portions of the joints just described. Such flats may or may not be needed to seat the tops of beams 24 and 25, at least the flattening need not be of the same degree, since the chords 10 arch away from the outer edges of the beam.

The nose 26 of the rib is shaped by similarly building the nose portion of the chord 10. In this case the flat of the upper portion is lapped over and welded to the flat of the lower portion as indicated in Fig. 8. The tail of the rib is constituted by similarly joining together flattening .portions at the rear ends of the chords 10 as shown in Fig. 9.

The annexed claims should protect to me all modifications of my invention which fall within its generic spirit.

What I claim as new and useful and desire to protect by Letters Patentis 1. The method of forming truss joints which consists in bending continuous stock to form two integrally joined members and the angle "between them and thereafter forming a bead in the stock extending around the bend and internally of the angle.

2. The method of forming truss joints which consists in bending channel stock to form two contiguous truss members integrally joined together and the angle between them, flattening the channel stock around the apex of the angle at the time of bending, and thereafter forming a bead internally of the angle-.-

3. The method of forming truss joints angles between integral structural members at an angle to each other which consists in directing the draw on a line bisecting the angle from its exterior and stepping the draw on opposite sides of the apex whereby to draw the metal away from the apex.

6. The method of drawing beads in the angles between integral structural members at an angle to each other which consists in directing the draw on a line bisecting the angle from its exterior and stepping to sufficient depth in the line of draw to cause the steps to be drawn first on opposite sides of the apex, and then the apex whereby to draw the metal away from the apex.

In testimony whereof he hereunto afiixes his signature.

EARL J. W. RAGSDALE.

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