US 3085596 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
April 6, 1963 w. E. REJESKI 3,085,596
COLLAPSIBLE TUBING Filed Aug. 31. 1959 /a mum/for l/l ////0m E. Re eSk/ By his af/omeys United States Patent 1 3,085,596 COLLAPSIBLE TUBING William E. Rejeski, Farmington, Conn., assignor to The Wiremold Company, West Hartford, Conn., a corporation of Connecticut Filed Aug. 31, 1959, Ser. No. 837,146 4 Claims. (Cl. 138-131) This invention relates to collapsible two-element tubing made from strips of metal and fabric or other suitable flexible material capable of being wound helically in continuous lengths of any desired dimension with the edges of the metallic and flexible spiral strips locked together.
The invention is an improvement on .the invention disclosed in the A. E. Chernack Patent 2,417,676 issued March 18, 1947.
It is an object of the invention to provide an improved construction of collapsible tubing which will permit much sharper or tighter bends than heretofore without requiring additional material or more complicated or more expensive construction.
A related object is to provide improved tubing construction having the above-mentioned characteristics which also provides a smoother interior surface at the bend of the tubing than heretofore.
Other advantages of the invention will become apparent as it is described in connection with the accompanying drawing.
In the drawing:
FIG. 1 is a side elevation view of tubing embodying the invention.
FIG. 2 is a fragmentary perspective View of the new tubing, partly in section, the section 'being taken by cutting the tubing along line 22 of FIG. 1.
FIG. 3 is a section view of the bend in the tubing of FIG. 1 with the section being taken by making a cut along line 3-3 of FIG. 1.
In collapsible tubing to which this invention relates, a metallic strip is continuously wound in spiral form on known machines. The edges of the strip 10 are reversely bent outwardly to form flanges 12 and 14 which are bent down toward the outer face of the strip upon edges of a flexible strip 18 of any suitable material. Treated or untreated textile fabric and plastic sheet materials are typical examples that are commonly used, but the invention is not limited to such materials.
The edges of the metallic strip frictionally and securely hold the edges of the flexible strip very firmly as the edges of the metal are bent down upon and clamp the edges of the flexible strip between the flanges and the body of the metal strip.
Tubing of the sort thus far described has been used in large quantities satisfactorily for many years for many purposes. It has been made in various diameters with strips of varying width. But one problem which for a long time has defied solution was the inability to bend the tubing in as tight bends as desired in many instances.
In many diameters of tubing, short lengths of tubing could be bent only with diflicul-ty even into a right angle bend due to the edges of each metal spiral being maintained in abutment with its neighbors with the flexible strip being folded inwardly. Thus, the dimensions of the fabricated metal spiral, together with the thickness of the flexible strip (two thicknesses being between each pair of abutting metal strip edges), imposed a definite limitation on the angularity of the bend to which such tubing of any given diameter and any given width of metal and flexible strips could be bent. In short lengths, it was never possible to bend the tubing into U-shape and fre quently it was impossible within the limited length avail- 3,085,596 I Patented Apr. 16, 1963 ice able for bending, to bend the tube at a sufficiently tight bend to satisfy the most advantageous requirements.
According to the present invention,provision is made for the spirals of the metal strip to fold upon one another within the inside curve as the tubing is bent. This not only enables more convolutions of the metal spiral to be put into a given arc, but also allows the fabric to fold inwardly and not to interfere with the folding over or overlapping of the metal spirals. This objective is accomplished by providing a slight bend 16 in the metal strip along its length parallel to the edges of that strip or, in other words, along or parallel to its longitudinal axis. As a result of this angulation, one edge of the metal spiral is offset outwardly slightly with respect to the other; or in other words, the arc of curvature of one edge of the metal strip is of greater diameter than the other edge of that strip.
The angle of the bend preferably is in the neighborhood of 30 from its original flat position or, referring to the oblique angle, in the neighborhood of This angle may vary consider-ably and is not critical. It is necessary only that the offset of the neighboring edges of adjacent spirals of the metal strip be suflicient to allow the edges of one convolution to fit under the adjacent edge of the next convolution so that when the tubing is bent, the convolutions may nest together, as shown in FIGURE 3.
The offsetting and the folding or nesting together of the convolutions allows the angularity of the bend to be at least double what heretofore was possible with tubing having the same metal and flexible strip materials and the same dimensions and diameter. For example, a 16 inch length of tubing of 4 inch diameter can now be bent into a complete U and almost so that the opposite ends touch, in contrast to the bending ability heretofore being limited to not more than about a right angle for tubing of the same size, length and materials.
In addition to the ability to bend the improved tubing into so much tighter bends, the nesting of the metal spirals and the flexible strip results in less of the flexible strip being forced into the tube and, hence, a smoother interior surface is provided with concomitant improvement in fluid flow within the tubing.
Modifications within the scope of the invention will occur to those skilled in the art. Therefore, the invention is not limited to the exact form and dimensions illustrated and described.
What is claimed is:
1. A flexible tubing structure adapted for flex-ure into short radius angular bends comprising a continuous metallic strip in helical form having edge and body portions, the edge portions being reversely bent and lying adjacent the body portion, a strip of flexible material disposed and clamped between the adjacent edge and body portions of each adjacent convolution of said metallic strip, the body portion of said metallic strip being bent parallel to said edges throughout the length of said strip such that the diameter of one edge of the convolutions formed by the metallic strip is greater than the diameter of the opposite edge thereof, the smaller diameter edge portion of each convolution being opposed by the larger diameter edge portion of the next adjacent convolution whereby when said tube is bent to a maximum angle of curvature the larger diameter edge portions of each convolution will overlap the smaller diameter edge portions of each adjacent convolution at the innermost radius of curvature and a minimal amount of flexible material is thereby folded into the interior of the tubing.
2. A flexible tubing structure adapted for flexure into short radius angular bends comprising a continuous metallic strip in helical shape, a helical strip of flexible material interposed between and affixed to the edges of the metallic 3 strip between each convolution thereof, said metallic strip having its edges displaced, one with respect to the other, such that the circumference of one edge of each convolution of the metallic strip exceeds the circumference of the other edge thereof, said strip and said flexible material in each convolution being so aflixed that the edge of the metallic strip having the smaller circumference will nest, when said tubing is bent to a maximum of curvature, Within the larger circumference of the next adjacent convolution thereof at the innermost radius of curvature of 10 said metallic strip.
3. Flexible tubing structure as claimed in claim 2 wherein said edge portions of said metallic strip are reversely bent toward the same face of the body portion of the metallic strip.
4. Flexible tubing structure as claimed in claim 2 wherein said edge portions of said metallic strip are reversely bent outwardly of the tubing and overlie the same face of the body portion of the metallic strip.
References Cited in the file of this patent UNITED STATES PATENTS 1,030,016 Rosenthal June 18, 1912 1,905,824 Dysthe Apr. 25, 1933 2,417,676 Chernack Mar. 18, 1947 2,841,183 Rejeski July 1, 1958