US2895509A - Flexible hose - Google Patents

Description

July 21, 1959 w. c, 'nc o 2,895,509

FLEXIBLE HOSE Filed July 11. 1955 United States FLEXIBLE HOSE Application July 11, 1955, Serial No. 521,143

4 Claims. (Cl. 138-49) This invention relates to flexible hose, and more particularly to axially collapsible ducting formed from thin strip material sewn to a helical reinforcing member.

There are a great variety of duct applications where it is necessary to handle large volumes of gaseous fluids as economically as possible and without danger of leakage. Ventilating and air conditioning is but one of many fields of use for such ducting. A construction presently available has the desired flexibility and is inexpensive to make. However, it is subject to several disadvantages rendering it unsuitable for certain applications and detracting markedly from the optimum characteristics desired for all applications. For example, the piercing of the strip material by needle and thread as required by the sewing operation forms openings through which the fluid conveyed escapes. Naturally, such escape increases with the pressure. This represents an objectional loss under any circumstances and a serious one where the gas is valuable, poisonous, oboxious or explosive in nature.

Another short-coming of sewing ducting, as heretofore made, is that the helical reinforcing subjects the lapped edges of the stripping to concentrated wear at points overlying the reinforcing leading to early failure of the duct. This may occur as a premature rupture of the side wall or the escape of the reinforcing from the seam.

Both of these major objections, together with numerous related drawbacks, have been circumvented in a positive manner by the present invention without adding to the cost in any substantial way. Moreover, the utility, efficiency, service life and over-all usefulness of the duct are increased immeasurably when made in the manner disclosed herein.

Figure 1 is a fragmentary side view of the novel duct in the process of manufacture;

Figure 2 is a View taken along line 2-2 on Figure 1 and showing the manner of feeding the several components to the processing stations;

Figaro 3 is a sectional view along. line 3-3 on Figure 1 showing the structure at the duct seam;

Figure 4 is a fragmentary sectional view of the sealing and buffer strip; and

Figure 5 is a fragmentary plan view of the duct seam with portions of the buffer strip broken away.

The ducting, generally designated 10, may be formed from a continuous web or strip 11 of suitable impervious material. Usually, a cotton fabric is employed and this is rendered impervious by any suitable coating of an elastomeric, plastic or other well-known flexible nature. When using a fabric, it is desirable that the warped threads run lengthwise to the edge of the strip. Obviously, strip 11 may also be formed of various other materials including the synthetic filaments, fiberglass, sheet elastomers, sheet plastics, etc. The strip material is fed from a supply roll 12 mounted on a shaft 13 supported in some convenient manner above the sewing machine generally indicated at 14.

atent The sewing machine is of a conventional commercial type having a pair of needles 15, 15 spaced suificiently to straddle the rigid reinforcing element 16. The latter is held captive between the overlapped. edges of strip material 11 by stitching 17 in the manner clearly shown in Figure 3. As made clear by Figure l, the leading edge 18 of stripping 11 overlaps the trailing edge 19 of the previous turn or convolution sufliciently to enclose the reinforcing wire 16 and provide a firm anchorage for stitching 17. In the present illustration, the reinforcing helix consists of wire but it will be clear that it may comprise rigid plastic material, or the like, readily formed into a helix of uniform diameter...

The initial step in the formation of a length of the ducting is to prepare the reinforcing helix 16 from stiff wire or other suitable material. Preferably, the helix is formed with a pitch. or spacing between adjacent turns substantially identical with that desired in the finished ducting. A helix of the required length is slipped over the left-hand end of cantilever arm 20 of the sewing machine. Stripping 11 is then pulled from the supply roll 12 and formed into a circle of the desired diameter for the finished duct with the trailing edge of the first turn underlying the leading edge of the second turn. The end of the leading turn of helix 16 is then fed between the overlapped edges of the seam as the latter is fed beneath needles 15, 15 of sewing head 21. The operator then guides the stripping to the machine along with the wire helix in such manner that a seam of the requisite width is formed to accommodate the wire reinforcing and the two rows of stitching 17 on either side of it.

As soon as one complete turn of the ducting is formed, the forward end of the helix is in position to pass between a flat roller 22 and a grooved roller 23. Roller 22 presses upwardly against the inside wall of the ducting and is supported on a bracket arm 24 anchored to the body of the sewing machine. Grooved roller 23 is supported from above by means of a suitable bracket 25.

As the first turn of the helix passes between these rollers, the operator inserts the end of sealing strip 26 beneath roller 23. This strip is formed of any suitable impervious pliant material such as rubber, plastic or the like having a contour such as that illustrated in Figure 4-. An inexpensive and highly efficient strip may be extruded from polyvinyl chloride. The opposite edges 27, 27 are preferably feathered to a thin edge so as to merge smoothly with the outer surface of the duct in the manner shown in Figure 3. The central portion 28 is relatively thick and humped to fit about the reinforcing wire and the outer layer of the seam. When so formed, the sealing strip presents a pleasing appearance and conceals the reinforcing wire and seam very effectively. In fact, the viewer gains the impression that the sealing strip itself accounts for the rigidity and selfsupporting characteristics of the ducting.

Before the forward end of the stripping is inserted beneath roller 23, its under side is coated with a suitable cement or bounding agent as by means of the fountain brush applicator 29 shown in Figure 2. Sealing strip 26 may be supplied from a supply roll 36 supported conveniently in front of the sewing machine. Preferably, it passes through suitable guide and tensioning rolls positioned between supply roll 31) and applicator 29. If the applicator is spaced some little distance in front of roller 23, the cement will have an opportunity to partially set and become tacky before being pressed firmly against the seam by the rollers. Rapid curing of the cement is desirable and this may be facilitated by the provision of heating lamps along the sides of the duct or by blowing heated air over the duct. As the ducting continues to emerge from the sewing station,

its foremost end will be engaged by supplemental supporting rollers 32, 32 carried on brackets 33, 33 at the opposite lower sides of the duct. Rollers 32 are provided with wide grooves which accommodate the outwardly protruding portion of the seam in a manner to feed the duct axially to the left as it rotates past the sewing needles.

The completed duct has the general appearance indicated in Figures 1, 3 and 5. One of the features of ducting made in the manner described above is a smooth inner surface of substantially uniform diameter throughout. This is achieved by laying the reinforcing helix on top of the trailing edge of the first turn of stripping. The leading edge of the next turn is then superimposed on the helix and held pressed inwardly about the sides of the helix by the two rows of stitching 17, 17. The resulting spiral bulge along the outer side of the duct is largely concealed, however, by the shape and design of sealing strip 26.

Ducting having a substantially uniform inner diameter is highly desirable from a fluid handling standpoint, but results in a construction in which the outer layer of the seam bears substantially the entire brunt of the abrasive action to which the ducting is subjected in normal usage. This hazard is entirely eliminated by the present construction due to the protection afforded by the pliant abrasion resistant sealing strip 26. This stripping not only serves to hold the outer wall of the ducting even further removed from supporting surfaces, than is the case without the sealing strip, but enables it to withstand the most abusive handling before wearing through to the underlying seam. And, of course, it is self-evident that the impervious sealing strip, together with the bonding cement, positively seals the openings made by stitching 17 against any possibility of leakage.

It will be apparent from the foregoing that the ducting can be formed in various styles and sizes and can incorporate numerous constructional variances without departing from the principles of this invention. For example, in certain applications of the duct it might be desirable to eliminate the outwardly protruding helix and tolerate the decreased flow efl'iciency resulting when the helix protrudes inwardly. Likewise, a compromise between these two alternates could be employed by forming a semi-circular groove on arm 20 between needles and 15. And, of course, stripping 11 could be much narrower or much wider than that indicated in Figure 1. Moreover, it is not necessary that the sealing strip 26 have a cross-sectional contour illustrated in Figure 4, as flat stripping is quite satisfactory where external appearance is of no particular importance and the advantages of the special contour can be sacrificed. Also, the sealing strip could be applied over the inner side of the seam if this should be required for a particular duct application. It is therefore to be understood that these and the like variants are intended to fall within the scope of the attached claims.

I claim:

1. Axially collapsible flexible ducting comprising a strip of impervious flexible material wound helically with the leading edge of one turn overlapping the trailing edge of the adjacent turn to form a seam, a helically wound reinforcing member positioned within said seam, at least two rows of stitching locking said overlapped edges together with said reinforcing helix held captive between said rows of stitching, and a strip of impervious flexible material wider than the distance between said rows sealed to the outer wall of said ducting over said rows of stitching so as to reinforce said ducting at said overlapped edge and to seal said ducting against leakage through the openings made by said stitching.

2. Axially collapsible flexible ducting as defined in claim 1 wherein said sealing strip is made from extruded flexible plastic material and is bonded to said ducting across said rows of stitching.

3. In flexible ducting of the type having a flexible cylindrical side wall formed of impervious thin-walled material, a stilf helical wire reinforcing member encircling said wall, and helical rows of stitching anchoring said reinforcing member to said side wall; the improvement comprising a narrow strip of impervious pliant material wound about said ducting and cemented thereto in a helical path coinciding with that of said wire reinforcing member and of said stitching rows and serving to seal said stitching against leakage as well as to protect the stitching and the ducting adjacent said reinforcing member against abrasion.

4. Flexible ducting having a readily flexed side wall formed of impervious fabric stripping wound spirally with the leading edge of one turn overlapping the trailing edge of an adjacent turn to form a seam; a wire helix coextensive with said seam for holding the side walls of said ducting against radial collapse, parallel rows of stitching holding the overlapped portions of said seam together and said wire helix captive within said seam; and a narrow extruded strip of plastic material having a thick transverselyhumped central portion straddling said wire helix and tapered edges bonded to the sewn portion of said seam from end-to-end thereof so as to seal said ducting against leakage where the walls are pierced by said sewing.

References Cited in the file of this patent UNITED STATES PATENTS 1,259,833 Burns Mar. 19, 1918 2,016,601 I-Ilavaty Oct. 8, 1935 2,140,638 MacLachlan Dec. 20, 1938 2,371,991 Harding Mar. 20, 1945 2,452,047 Hamblin Oct. 26, 1948 2,475,389 Hersey July 5, 1948 2,804,095 Schauenburg Aug. 27, 1957 FOREIGN PATENTS 649,351 France Dec. 21, 1928

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