US 2196708 A
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April 9, 1940. r J 5 RE) REINFORCED THIN WALL TUBING Filed 001;. 26, 1936 fig] I NVENTOR 6 v BY- 4 JAMrgJ REID I ATTORNEY.
Patented Apr. 9, 1940 UNITED STATES PATENT OFFICE REINFORCED THIN WALL TUBING James S. Reid, \Shaker Heights, Ohio, assignor,
by mesne assignments, to The Standard Products Company, tion of Ohio Port Clinton, Ohio, a corpora- Application October 26, 1936, Serial No. 107,571
tion which may be bent into an annulus without buckling or wrinkling of the outer surface.
Another object is to provide a continuous method of forming internally reinforced tubing of fiat strip stock.
A more specificobject is to form tubing of substantially circular cross-section with integral, internal radial reinforcing means.
Other objects and advantages will become apparent from the following specification wherein reference is made to the drawing, in which:
Fig. 1 is a plan view of a steering wheel rim and spokes formed with the tubing of the present invention;
Fig. 2 is an enlarged perspective view of a length of tubing embodying the principles of the present invention;
Fig. 3 is a sheet of metal illustrating the manner of preparing the same for folding the same to form the tube;
Figs. 4 and 5 are end elevations of the sheet of tubing illustrating successive stages of the folding operation;
Fig. 6 is an enlarged fragmentary view of a length of the tubing, part of the circumferential wall being removed for clearness in illustration; Fig. 7 is an elevation of a portion of the tubing spirally formed for forming steering wheel rims; and
Fig. 8 is a perspectiveview of a finished rim. Referring to Fig. 2, the tubing comprises a sheet of relatively thin metal I having its marginal portions preformed, so that, upon folding, the main body of the material is rolled to tubular shape with the margins disposed interiorly and defining radial reinforcing spokes 2, 3, 4' and 5, respectively.
For eifecting this folding operation, the metal sheet I is passed through successive sets of 4 forming rolls by which it is first folded along its lateral margins to provide the spoke portions 2 and 5, each equal substantially to the radius of the finished tubing. These portions are disposed'at substantially 120 to the plane of the sheet. Next, the portions 3 and 4 lying between the margin portions 2 and 5 and the central portion of the sheet are folded substantially 90 to the plane of the sheet in the same direction as the margins 2 and 5. The portions 3 and 4 are likewise each equal in length to the radius I of the finished tubing.
, Substantially concurrently with the folding of the portions 3 and 4 to the 90 position, the central portion of the sheet of material is warped centrally along a gradual curve, as indicated at 6, and toward the lateral limits is reversely warped to provide reversely curved portions 1 and 8, which merge with the curved portion 6. The portions 1 and 8 are substantially the same radius as the finished tubing.
With the sheet in this condition, it is next folded in a direction opposite to the curve of the curved portion 6, as indicated bythe arrows 9 in Fig. 5, so as to dispose the curved portions 6, 1 and 8 in enclosing relation to the spoke portions 2, 3, 4 and 5. The curvature of the central curved portion 6 is such that upon folding the sheet to form the finished tubing, the curvature of the portion 6 will be reversed and conform to and provide a continuation of the portions 1 and 8. During this folding action, the initially outer faces of the portions 3 and 4 are juxtaposed, as illustrated in Fig. 2, and in dotted lines in Fig. 5, thus defining a single, double-thickness spoke spaced 120 from the spokes 2 and 5.
Since all portions 2, 3, 4 and 5 are equal in width tothe radius of the finished tubing, the spokes 2 and 5 firmly abut the inner wall surface of the finished tubing.
The tubing is preferably formed by the forming rolls with sufiicient stress to set it with a radius slightly under the final radius so that the internal stresses of the metal resiliently force and hold the spokes 3 and 4 firmly in juxtaposition to provide a substantiallyclosed joint.
If the tubing is to be used for spokes, or without axial warpage, no other operation thereon is necessary. If the tubing is to be warped axially to form a steering wheel rim annulus, it is preferably warped with the dual spoke portions 3 and 4 lying in a plane defined by the tubing axis after warpage, and extending from the axis of the tubing toward the center of curvature. such a formation of the tubing, spoke portions 2 and 5 extend in a direction away from the center of curvature beyond the axis of the tubing and therefore must necessarily elongate or yield slightly during the warping operation to compensate for the increase in circumference resulting at their outer limits relative to the circumference at the center of the tubing.
Since the dual spoke portion cannot be contracted, and cannot expand at its juncture with the tubing wall, but only at its juncture with the spoke portions 2 and 5, the warpage must occur by expansion outwardly from the juncture of the dual spoke portions 3 and 4'with the tubing wall. To provide for this expansion, the sheet is preformed with a series of slits Hi, the slits l being spaced longitudinally along the margins of the sheet and extending transversely of the marginal portions defining the spokes. Each slit extends from the outer margin of the sheet I entirely to the inner margin of the associated spoke portion 3 or 4, as the case may be.
If the tubing is to be used for steering wheel rims and the like, it is preferably shaped by the formingrolls into a continuous spiral tubing of comparatively flat convolutions or pitch after the folding operation. For forming therims from such structure, each complete convolution of the coil is severed by a. suitable metal cut-off, thus separating the coil into a plurality of complete, but separate, spiral loops, such as illustrated in Fig. '7. To form the rim therefrom, the ends of p the loop are sprung together and butt welded,
thus providing a continuous rim. In forming the tube from the flat stock, obviously it may be continuously fed through the forming mechanism from suitable coils of 'flat strip so that the process is continuous.
Having thus described my invention, what I claim is:
1. A length of tubing having a curved axis comprising a single strip of sheet metal providing a tubular wall, the strip having marginal portions extending radially from the wall interiorly of the tubing, the marginal portions being split at intervals from the outer edges, the outermost portions of the marginal portions being angularly disposed with respect to .the remainder of the marginal portions and. abutting the interior of the tubular wall at their edges.
2. A length of tubing bent in the form of an annulus and comprising a single strip of sheet metal providing a tubular wall, said strip having marginal portions extending radially from the wall interiorly of the tubing, the width of each of said portions being substantially twice the radius of the tubular wall, said marginal portions being split at regular intervals from the outer edges to facilitate the bending operation, the outermost half of said marginal portions being angularly disposed with respect to the remainder of the marginal portions and abutting and supporting at equally and circumferentially spaced zones the interior of the tubular wall at their edges.
3. A circular ring of reinforced tubing comprising a single strip of sheet metal providing a tubular wall, the strip having marginal portions directed substantially radially from the wall interiorly of the tubing, and juxtaposed in face to face relation, the outermost sections of the marginal portions being angularly disposed with respect'to each other and abutting the interior of the tubular wall at their edges, said marginal portions being split at regular intervals to facilitate bending the tubing in a plane defined by the juxtaposed marginal portions.
4. An annular reinforced tubular ring comprising a single strip of sheet metal having atubular wall of uniform circular cross section, said strip having marginal portions folded radially inwardly from the tubular wall to the central axis thereof, the innermost section of each of the marginal portions being juxtaposed in face-to-face relation with each other from the tubular wall to the central axis, the outermost sections of said marginal portions extending beyond said central axis and being angularly and equally disposed with respect to each other and to the said innermost sections, the said marginal portions being split at regular intervals to facilitate the bending operation of the tubing in a plane defined by the said innermost sections of the marginal portions.
JAMES S. RED).