Perforate Conduit

Abstract

A perforate conduit comprising an elongated tubing provided with at least one series of longitudinally extending, spaced apart ridges formed in the wall of and extending outwardly from the surface of said tubing. At least one opening is provided in each of said ridges so as to provide communication between the exterior and interior of said tubing.

Description

This invention relates to a perforate conduit.

Land drainage conduits have commonly comprised a plurality of joints of pipe, commonly tile pipe. These joints of pipe, in various lengths of up to about 4 feet, are commonly laid end-to-end in excavations with spaces left between the ends of the joints to provide entry into the pipe. Said joints were then wrapped with screen, water-resistant paper, etc., so as to prevent soil or other debris from entering the pipe. Installations of this type have been widely employed in foundation drainage systems, distribution laterals on septic tanks, etc. Such installations require relatively large numbers of the relatively short lengths of pipe. The costs of such installations, and particularly labor costs, have been great.

It would be desirable to reduce these costs. One way of accomplishing cost reduction would be to employ longer lengths of conduit. It is difficult to manufacture and handle tile pipes in lengths greater than about 4 feet. In recent years, plastic pipes or conduits formed of polyethylene, polypropylene, copolymers of ethylene and propylene, copolymers of ethylene and butene, and other plastics have come into widespread use in many applications where metal pipe or conduit was formerly employed. Pipes or conduits formed of such plastics can be fabricated in longer lengths than metal or tile pipe. Longer lengths of the pipe or conduit will eliminate a large majority of the joints necessary in any given drainage system. The elimination of the joints would require the provision of suitable openings into the pipe or conduit so as to provide communication between the exterior of the pipe and the interior of the pipe so that water can enter the pipe. Provision of suitable openings has presented problems.

The present invention provides a solution for the above problems by providing a perforate conduit which is particularly well adapted to be employed as a land drainage conduit, or as a distribution conduit such as in underground irrigation systems, laterals in septic tank distribution fields, etc. The perforate conduit of the invention is preferably fabricated from one of any suitable thermoplastic extrudable materials such as polyethylene, polypropylene, copolymers of ethylene and propylene, copolymers of ethylene and butene, and other suitable plastics. The perforate conduits of the invention can be fabricated in any suitable lengths. Preferably, the conduits are fabricated in lengths of up to 40 feet when made of rigid plastic. However, said conduits can be fabricated in greater lengths when made of flexible plastic. Thus, it is within the scope of the invention to fabricate the conduit in a continuous extended length, wind same on a reel, and field cut to desired length during installation. Any of said lengths can be readily joined by methods known in the art.

Thus, according to the invention, there is provided a perforate conduit, comprising: an elongated tubing; at least one series of longitudinally extending, longitudinally spaced apart ridges formed in the wall of and extending outwardly from the surface of said tubing; and at least one opening provided in each of said ridges so as to provide communication between the exterior and the interior of said tubing.

Further according to the invention there is provided a method of forming a perforate tubular conduit, which method comprises, the steps of: forming an elongated tubing by extruding a plastic material from an extrusion means; forming at least one series of longitudinally extending, longitudinally spaced apart ridges in the wall of and protruding from a surface of said tubing, while said tubing is still in a plastic state; and forming at least one opening in each of said ridges so as to provide communication between the exterior and the interior of said tubing.

FIG. 1 is a perspective view of a joint of perforate conduit in accordance with the invention. FIG. 2 is a partial cross section view of a perforate conduit in accordance with the invention, illustrating one method for forming the openings in the conduit. FIG. 3 is a cross section of the perforate conduit of FIG. 1, taken along the lines 3--3. FIG. 4 is another partial cross section view illustrating another method of forming the openings in the perforate conduits of the invention. FIG. 5 is a cross section view of another perforate conduit in accordance with the invention. FIG. 6, together with FIG. 7, is a diagrammatic representation of apparatus which can be employed in fabricating the perforate conduits of the invention.

Referring now to the drawings, wherein like reference numerals have been employed to denote like elements, the invention will be more fully explained. In FIG. 1, there is illustrated a perforate conduit in accordance with the invention which comprises an elongated tubing 10 which is provided with at least one series of longitudinally extending, longitudinally spaced apart "hollow" ridges 12 and 14 formed in the wall thereof, and extending outwardly from the outer surface of said tubing. At least one opening 16 is provided in each of said ridges so as to provide communication between the exterior and the interior of said tubing. Preferably, said spaced apart ridges are aligned longitudinally of the tubing as illustrated. However, it is within the scope of the invention for said ridges to be nonaligned. If desired, and preferably in most instances, the tubing can be provided with a plurality of series of ridges, e.g., a first series such as 18 and 20, and one or more other series such as 22 and 24, and 12 and 14. Said series of ridges are spaced apart from each other peripherally of the tubing, as illustrated. In the embodiment of the invention illustrated in FIG. 1, said ridges extend outwardly from the outer surface of the tubing. This embodiment is frequently preferred when the conduit of the invention is employed in an irrigation system. Preferably, said tubing will be generally cylindrical or circular. It is within the scope of the invention, however, for said tubing to be oval, rectangular, or any other shape in cross section.

When a plurality of series of ridges is provided, one preferred arrangement is that said ridges be arranged in spaced apart groups with each group comprising a central ridge, such as ridge 12, and two side ridges such as 18 and 22 disposed substantially parallel to said central ridge. When the perforate conduits of the invention are employed 24 a drainage conduit, the conduit is installed so that said ridges with the openings therein are provided in the upper portion, e.g., upper one-half, of the conduit. The bottom of the conduit then provides an unobstructed surface for conveying the liquid being drained. In such instances, each series of ridges can be spaced apart peripherally from its associated series of ridges any suitable distance so long as the ridges are formed in the upper portion of the conduit. For example, when employing two series of ridges, they can be up to 180.degree. apart, measured from opening to opening. In a conduit provided with three series of ridges as illustrated in FIG. 1, a convenient and sometimes preferred distance for the side ridges to be spaced from the central ridge is within the range of about 10.degree. to 80.degree., preferably about 60.degree.. When employed in distribution systems, such as an irrigation system, the conduit is installed so that said ridges with the openings therein are provided in the lower one-half of the conduit.

FIG. 2 illustrates the appearance of a ridge, e.g., ridge 12, as it is first formed. In one presently preferred embodiment of the invention, the portion 26, shown by dotted lines, is removed as by sawing so as to provide opening 16. FIG. 3 illustrates the cross-sectional appearance of a perforate conduit of the invention formed in this manner and containing three series of ridges thereon. The openings 16 in said ridges can be any suitable shape. In one presently preferred embodiment of the invention, they are elongated and extend substantially the full length of the ridge. Said openings 16 can be holes or spaced apart slots formed in the top of the ridge, similarly as illustrated by openings 16' in the inwardly extending ridges of FIG. 5, or can be holes or spaced apart slots formed in the side of the ridge as illustrated in FIG. 4. It will be understood that said slots when placed in the side of the ridge do not extend the entire length of the ridge.

FIG. 5 illustrates another embodiment of the invention wherein the ridges, e.g., 12', exend inwardly of the tubing 10' from the inner surface thereof. The above description of the spacing, grouping, number of series of ridges, etc., given in connection with FIG. 1 also apply to FIG. 5. The embodiment illustrated in FIG. 5 is frequently preferred as a drainage conduit.

FIGS. 6 and 7 illustrate schematically the formation of a conduit of the invention from an extrudable plastic material. Said conduits are formed by first extruding a suitable plastic material from an extruder 28 in known manner. The conduit is still in plastic condition as it leaves the extruder. After leaving the extruder, the conduit enters the molding station which comprises two endless belts 30 driven in known manner by means not shown. When forming the embodiment illustrated in FIGS. 1 and 3, said belts 30 each have a series of half-molds 32 and 34 mounted thereon. Each alternate half-mold 32 contains grooves 36 formed in the face thereof. The number and arrangement of said grooves 36 will depend upon the number and arrangement of ridges desired in the finished conduit. In said molding station, the conduit wall while in a plastic state is forced into said grooves 36 by means of internal pressure maintained within the conduit in known manner, or by vacuum applied to the back of the half-molds in known manner.

After leaving the molding station, the conduit passes through a cooling station not shown. The conduit then proceeds to a cutting station where rotating saws 38 saw off the top of the ridges, as illustrated in FIG. 7. If desired, openings 16 or 16' can comprise a series of holes drilled from the apex of the ridge similarly as illustrated by openings 16' in the inwardly extending ridges of FIG. 5. Or, if desired, said saws can be employed to form slots in the sides of the ridges similarly as illustrated and described above in conection with FIG. 4.

When forming the embodiment illustrated in FIG. 5, the grooves 36 in the alternate half-molds 32 will be replaced with protrusions. In the molding station said protrusions are pressed into the still plastic conduit to form the internal ridge(s) such as 12'. Opening 16' can then be made with a saw or drill.

The perforate conduit of the invention possesses a number of advantages over distribution or drainage conduits of the prior art. The conduits of the invention can be readily formed from inexpensive materials such as the various plastics commercially available. Such conduits are thus more economical, and have good radial resistance, but still have sufficient resiliency to be highly resistant to crushing. Such conduits are easily installed. In installing in the earth, it is preferred to cover, or surround, at least the portion of the conduit containing the openings 16 or 16' with a porous fill such as a properly sized pea gravel. Said conduits are essentially inert to environmental conditions.

While certain embodiments of the invention have been described for illustrative purposes, the invention is not limited thereto. Various other modifications or embodiments of the invention will be apparent to those skilled in the art in view of this disclosure. Such modifications or embodiments are within the spirit and scope of the disclosure.

Claims

I claim:

1. A perforate drainage and distribution conduit, comprising:

an elongated tubing of a resilient but rigid plastic material;

at least one series of longitudinally extending, longitudinally spaced apart ridges formed in not more than one-half of the wall of and exending from a surface of said tubing; and

at least one opening provided in each of said ridges so as to provide communication between the exterior and the interior of said tubing.

2. A conduit according to claim 1 wherein said ridges extend outwardly from the outer surface of said tubing.

3. A conduit in accordance with claim 2 wherein said spaced apart ridges are aligned longitudinally of said tubing.

4. A conduit according to claim 3 wherein a plurality of series of said ridges are provided in said tubing, and said series of ridges are spaced apart from each other peripherally of said tubing.

5. A conduit according to claim 4 wherein:

said tubing is generally cylindrical; and three series of said ridges are provided.

6. A conduit according to claim 5 wherein the ridges in said three series of ridges are arranged in spaced apart groups with each group comprising a central ridge and two side ridges disposed substantially parallel to said central ridge.

7. A conduit according to claim 6 wherein said side ridges are each spaced apart from said central ridge a distance within the range of from about 10.degree. to about 80.degree. .

8. A conduit according to claim 7 wherein each said opening in each said ridge comprises an elongated slot extending substantially the length of the ridge.

9. A conduit according to claim 1 wherein said ridges extend inwardly of said tubing from the inner surface thereof.

10. A conduit according to claim 9 wherein said spaced apart ridges are aligned longitudinally of said tubing.

11. A conduit according to claim 10 wherein a plurality of series of said ridges are provided in said tubing, and said series of ridges are spaced apart from each other peripherally of said tubing.

12. A conduit according to claim 11 wherein the ridges in said series of ridges are arranged in longitudinally spaced apart groups with each group comprising ridges which are substantially parallel with each other and are spaced apart peripherally of each other.

13. A conduit according to claim 12 wherein said tubing is generally cylindrical and said substantially parallel ridges are spaced apart a distance within the range of from about 10.degree. to about 50.degree. .

14. A conduit according to claim 13 wherein each said opening in each said ridge comprises an elongated slot extending substantially the length of the ridge.