IL105745A - Drip irrigation pipe with emiiters incorporated in a continuous internal strip and method of its manufacture - Google Patents

Description

"DRIP IRRIGATION PIPE WITH EMITTERS INCORPORATED IN A CONTINUOUS INTERNAL STRIP AND METHOD OF ITS MANUFACTURE" n>>p¾»ni» i s" "nm* nonn *i«noo »n>ja oaa THE APPLICANTS: 1. DAVID KARMELI *m .1 2, YALDEI TEHERAN ST., 1*ino aim DANYA, HAIFA.

GIDEON PERI >15 llJTW. .2 15, MIV ZA YONATAN ST. ,15 itiii f 3) .an aim HAIFA.

DRIP IRRIGATION PIPE WITH EMITTERS INCORPORATED IN A CONTINUOUS INTERNAL STRIP AND METHOD OF ITS MANUFACTURE.

BACKGROUND OF THE INVENTION The present patent application is an addition to Patent Appl ication No. 098981.

The drip irrigation pipe according to patent application NO.098981 essentially comprises an extruded tube of a thermoplastic material and a strip of the same or similar material lengthwise fused tc the inside of the tube wall, the strip being characterised by that it contains on the surface fused to the tube wall a plurality of flow restricting passages which are spaced in close proximity. Each passage is in one of the shapes known in trickle irrigation emitters, such as a zigzag or labyrinth and has an upstream end provided with at least one perforation providing communication between the tube lumen and the passage, and has a discharge chamber at its downstream end permitting communication with the outside through an aperture to be pierced through the tube wall during manufacture .

The strip may be provided with closely spaced passages or with passages spaced according to the subsequent irrigation requirement, the discharge perforations being punched or cut through the tube during manufacture.

In order to provide a larger number of passages in close alignment, these may be of shorter length in various shapes as known to the art; they may, for instance, be U-shaped with inlet and outlet close to each other at the same end.

The pipe is manufactured by first impressing one side of a strip of a thermoplastic material with a plurality of spaced-apart flow-rest icting passages, for instance by passing it between two rollers provided with dies and counter-dies. Secondly, extruding a tube through a crosshead extruder and feeding the strip into the tube while fusing it to one side of the inside wall with the side containing the passages c+ntacting the tube wall. As a third step the tube wall is pierced at the points of the dis charge chambers.

SUMMARY OF THE INVENTION Manufacture of the drip irrigation pipe will now been described in detail, and includes essentially producing the strip, its insertion and fusing to the inside of the tube and piercing of the tube wall in the exact position of the discharge chamber.

Manufacture of the thermoplastic strip includes the following steps:- Extruding a strip of different cross sections to suit the final impression of the flow restricting passages, slightly cooling the extruded strip, passing the cooled strip between two rotating ro l l ers , whereof the central circumferential portion of the first roller is engraved with a number of negative flow restricting passages serving for impressing adjacent passages in the upper surface of the strip, and wherein this roller has two outwardly protruding collars embracing the sides of the second roller. The second roller is provided with at least one recess on its circumference communicating with a vacuum source, serving to draw out a knob or bulge protruding out of the opposite surface of the strip. The knobs are positioned opposite the discharge chambers of the passages or at a given distance therefrom and serve, at a later stage, for marking the exact spot for piercing the tube wall. finally cooling the strip and either coiling it on a drum for later use or for immediate insertion into the cross head of a second extruder for fusing it to the tube of the irrigation pipe.

As an alternative the knob or bulge may be produced by pressing the still soft strip material into the recess on the second roller without the aid of vacuum suction, the above method being, however, preferred.

Manufacture of the irrigation pipe includes the following steps : - Extruding a tube of a thermoplastic material by means of an annular die positioned in the cross head of a conventional extruder, while simultaneously feeding the manufactured and slightly heated strip into the cross head on a stationary, channel -shaped guide bar. The guide bar extends beyond the annular die and causes the strip to contact the inside of the extruded tube at a short distance therefrom where it is pressed onto the tube wall between rollers provided at the end of the guide bar and a roller on the tube outside, thereby fusing their respective surfaces. 105,745/2 cooling the tube with the inserted strip, passing the tube between rotating rollers so formed that they flatten the tube and cause the strip to be positioned at one end of the flattened tube, passing the flattened tube through a piercing device which includes a piercing device adapted to lower and insert a knife or punch through the tube wall into the discharge chamber of each flow restricting passage caused by the bulge or knob on the underside of the strip. coiling the completed pipe on a drum for storage and despatch.

The present invention permits the use of thin-walled tubes because these are strongly reinforced by the fused-in thin strips, whereby both weight and cost are considerably reduced and laying of the irrigation pipes in the field is facilitated. In addition, low cost is a very important factor in all cases where the pipes are used only during one season and are disposed of after one year's use.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a longitudinal section through an embodiment of the irrigation pipe according to Israeli Patent 98981, Figure 2 is a top view of the pipe shown in Figure 1 along line A-A, Figure 3 is a cross section through the pipe of Figures 1 and 2 along line B-B, Figure 4 is a cross section through the pipe of Figures 1 and 2 along line C-C, 105,745/2 Figure δ( A, B, C, D and EJ show cross sections of different types cf strip suitable for different shapes of flow passages, Figure 6 is a top view of a preferred embodiment of a strip showing an impressed flow passage.according to the present ^ . ... invention Figure 7 is a cross section through the strip of ngure 6 along line D-D, Figure 8 shows a general lay-out of the production line of the strip before its insertion into an extruded tube, Figure 9 is a side view of two rollers used in impressing '' flow passages into a strip of a thermoplastic material and to draw out a bulge from its underside, Figure 10 is a section through the two rollers o( Figure 9 showing the means for drawing out a bujge from its underside, Figure 11 shows a general lay-out of the production of the irrigation pipe, including extruding of th.:; hose and insertion f the strip, Figure 12 is a longitudinal section through the cross head of the extruder of Figure 11, including a channel -shaped strip guide, Figure 13 is a top view of the channe 1 -shaped guicl illustrated in Figure 12, Figure 14 is a section along line E-E of Figure 12, Figure 15 is a side view of the device serving to guide and to flatten the extruded hose and strip, Figure 16 is a side view cf the device illustrated in Figure 15, Figure 17 is a section through the device of Figure 15 along line F-F, Figure 18 is a section through the device of Figure 15 along line G-G, - 6 - 105,745/3 Figure 19 is a side view cf one embodiment of the hose piercing device, Figure 20 is an enlarged view of the piercing knife of the device shown in Figure 19, Figure 21 is a section along line H-H of Figure 20.

DETAILED DESCRIPTION OF THE DRAWINGS An embodiment of the drip irrigation pipe s shown in figures 1 through 4 essentially includes a Lube 1 of normal , medium or small wall thickness and a strip 2, both of extruded thermoplastic material. The strip is fused to the inside of the tube during its extrusion process, as will be explained further on. The strip contains on the side in contact with the tube wall a plurality of flow-restricting passages 3, each passage including an inlet chamber 4 and a discharge chamber 5. The inlet chamber communicates with the tube interior rhrough a series of openings 6 perforating the strip 2, and the discharge chamber communicates with the outside through an aperture 7 pierced through the tube hell , thus permitting water flowing through the irrigation pipe to enter the passage through inlet openings 6 and to trickle out to the plant to be irrigated through discharge chamber 5 and outlet aperture 7 at a pressure consideratly reduced by the flow resistance of passage 3. according to the present invention Another design of a flow restricting passage on the to surface of the strip is shown in Figure 6 and 7: herein the water inlet from the pine interior to the passage is in the form of several channels 6' extending from the inlet end of the labyrinth passage to the sides of the strip 2, permitting water to enter the passage from both sides of the strip after its fusion to the hose wall. The discharge chamber 5 at the outlet end of the passage includes three upstanding pins 8 intended for supporting the hose wall during piercing of the outlet opening 7. A bulge or knob 9 protrudes out of the underside of the strip, coinciding with the discharge chamber, but for certain designs of the piercing equipment the bulge may be longitudinally shifted by a given distance away from the position shown in the drawing.

The production line for the manufacture of a strip such as illustrated in Figures 1 through 7 is illustrated in Figure 8 : it includes an extruder for thermoplastic material I, a first cooling bath II, a device (III) for forming and impressing the strip with flow restricting passages and the aforementioned knobs or bulges on the underside, a second cooling bath IV, pulling rollers V, and coiling means VI. The novel feature of the line is illustrated in Figures 9 and 10 showing two parallel, cooperating rollers 10 and 11 which are rotated in opposite sense of direction by means of two shafts 12 and 13. Roller 10 comprises a raised central portion 14 engraved with the repeated pattern of the flow passages on its circumference and two outwardly extending flanges 15 defining the width of the strip to be formed. Roller 11 is cylindrical and comprises a number of recesses 17 in its central circumference equal to the number of passages on roller 10 which are connected to a source of underpressure by ductf18, 18' extending through the roller and the shaft 13 to a vacuum pump. The two rollers are adjusted in a manner that the formed knob or bulge 9 coincides with the position of the discharge chamber 5 or with a location at a given distance from the discharge chamber, as will be explained further down with reference to the device for making the discharge perforation from each emitter.

The general outlay of a production line of the" trickle irrigation pipe is illustrated in Figure 11:-it comprises, starting from right to left, a drum 20 containing the coiled strip 2, a strip puller 21, a strip heater 22, an extruder 23 including a cross head 24, a cooling bath 25, a device for guiing and folding the hose and strip 26, a perforating device 27 and a pipe puller 28. The completed pipe is finally coiled on a drum or stored in any other fashion. * Insertion of the strip into the hose and its fusion to the hose wall is illustrated in Figures 12, 13 and 14: The cross head 24 which is attached to the container of heated thermoplastic material (not shown) contains, in a known manner, a tubular die 30 for extruding the tube 1 which exits from the left hand-opening of the cross head. The pre-heated strip 2 is introduced into the crosshead from the right on a channel-shaped guide 31 which extends through the central openings of the tubular die beyond its outlet end, and is, in the portion extending through the die, provided with three rotating meedle rollers 33 preventing contact between the strip and the die interior. Two rollers 32 are fastened to the left hand end of the guide in spaced relationship urging the strip towards the tube wall, thereby fusing the two ill-soft bodies to each other. A third roller 34 is mounted on the outside cf the tube and is urged, by spring means or the like, into 105,745/2 the gap between the two rollers 32 in order to press the tube onto the strip* From this station the completed pipe is conveyed to the perforating station.

According to the present invention, the hose is completely flattened with the strip positioned along one edge of the flattened hose in order to permit perforating the hose exactly above the discharge chamber of the passage. Equipment (26) for this operation is illustrated in Figures 15 through 18:- it Includes a first station of two spaced apart pairs of grooved rollers 40 and 41 whereof each pair is in opposed distanced alignment and rotated in opposite sense of direction. The hose with the fused strip is fed between the rollers in such a manner that the strip is gripped in the opposed grooves and that the remaining portion of the hose is forced into oblong shape between the straighht portion of the rollers as shown in Figure 17 In cross section. The strip is then turned about a right angle as shown on the left side of Figure 15 and conveyed between two rollers 42 and 43 which compress the hose and strip into the shape shown in Figure 18.

As shown in Figures 19 through 21 the hose in flat shape is conveyed to the perforating device 27 which essntially comprises a pointed knife 50 at the front end of a lever 52 which is rocked about an axis 51 to effect its penetration through the hose into the discharge chamber 5 of the strip illustrated in Figures 6 and 7. The rocking motion is caused by the bulge 9 on the underside of the strip which, in the present case, is shifted by a distance d to the rear of the discharge chamber; as depicted in the drawing, a roll 53 is mounted on the rear end of lever 52 - 10 105,745/2 which cooperates with a second roll 54 underneath the strip and which raises roll 53 by force of bulge or knob 9 on the underside of strip 2 thereby rocking the lever and inserting knife 50 into the hose material slitting it. Additional rollers 55,56 guide the flattened hose into and out of the perforating device. The lever is adjusted by a control screw 57 and pulled back out of the slit by a spring 58.

The ready irrigation pipe is preferably left in flat state and pulled by puller device 28 (see Figure 11) to be coiled on a drum.

Certain modifications of the manufacturing equipment and process have been found to be feasable; It has been found that fusing of strip and hose after insertion of the hose along the guide 31 can be carried out without compression by rollers 32, 34 by passing the assembly through a vacuum chamber, (see Figure 12).

The pointed knife 50 of the perforation device may be replaced by a small-diameter trepanning drill or by a rotating saw.

Other modifications and improvements may be carried out both in regard to he drip irrigation pipe and its manufacture by a person skilled in the art, especially taking into account the development of new materials and new techniques. However, the present embodiment of the pipe has been found satisfactory both regarding its function and ease of handling; and the afore described equipment has proved itself suitable for fast production of the irrigation pipe at remarkably low cost.

Claims (19)

- 11 105.745/4

1. C L A I M S ! - 1. A drip irrigation pipe including integrally incorporated emitters, comprises an extruded tube of a thermoplastic material and a continuous strip of the same or a similar thermoplastic material of initially rectangular cross section containing a plurality of spaced-apart flow-restricting passages impressed on one of its surfaces below the normal level of said surfce and still within the contour of said strip, said strip being fused to the inside of said tube with said flow-restricting passages adjoining said tube wall, wherein each of said flow-restricting passages has an inlet end and a discharge end, each said inlet end communicating with the interior of said tube by means of at least one aperture in the shape of at least one groove Impressed on the surface containing said flow-restricting passages, said at least one groove extending from said inlet end to one side out of said strip, and wherein said discharge end of each flow-restricting passage communicates with at least one outlet aperture throughgoing said tube wall, the spacing of said flow-restricting passages being in accordance with the predesignated distances between said outlet apertures in said pipe.

2. The drip irrigation pipe of Claim 1, wherein each said inlet chamber communicates with said tube interior by means of several apertures in the shape of grooves impressed on said surface of said strip, each groove extending from said inlet chamber to one side of said strip.

3. The drip irrigation pipe of Claim 1, wherein said strip is provided with a knob or bulge protruding out of the surface of said strip opposite the surface containing said flow restricting passages, said knob or bulge being positioned opposite or slightly distanced from the location of said outlet chamber. - 12 105.745/5

4. A method of producing the strip as defined in Claim 3 including t e steps of extruding said strip by means of an extruder through a die of suitable cross section, impressing on one surface of said strip a plurality of spaced flow restricting passages, and forming said knob or bulge on the opposite surface, and cooling said strip for storage and/or subsequent use.

5. Equipment for manufacturing said strip as defined in Claim 4 including, an extruder comprising a die for forming said strip of a cross section suitable for subsequent impression of said flow passages, a bath for cooling said extruded strip, a strip-impressing device comprising two oppositely positioned rollers with their circumferences spaced at the final thickness of said strip and rotating in opposite direction at identical circumferential speed, whereof the circumferential surface of a first roller is engraved with a number of negative flow restricting passages serving for impressing adjacent passages into the surface of said strip to be fused to said tube, and whereof the second roller is provided on its circumference with at least one recess of a shape serving to form said bulge or knob on the opposite side of said strip,

6. * Equipment for producing the strip as defined in Claim 5, wherein said recess in said second roller communicates with a source of vacuum, serving to suck the strip material into said recess.

7. Equipment for producing the strip as defined in Claim 5, wherein said first roller is provided with two outwardly protruding collars embracing the sides of said second roller. 105,745/3 - 13 -

8. A method of manufacturing the drip irrigation pipe as defined in one of the Claims 1 through 3, comprising the steps of, extruding a tube of a thermoplastic material by means of a cross-head extruder, while simultaneously inserting said preheated strip into said extruder cross-head, forcefully approaching said strip to the inside of said tube causing the still-soft surfaces to fuse to each other with said flow-restricting passages positioned between said strip and the inside of said tube wall, cooling said tube and said fused strip, flatten said tube with said strip positioned along one lateral edge of said tube inside said tube, and perforating said tube over the location of said discharge chamber of each said flow-rest icting passage.

9. Equipment for carrying out the method of fusing said strip to said tube as defined in Claim 8, including, a strip heating device, a cross-head extruder provided with a tubular die of a size suitable for forming said tube, a channel-shaped guide extending through the lumen of said tubular die adapted to guide said strip through said die wthout contact thereto and to approximate said strip to the inside of said tube at a distance beyond said tubular guide, means for pressing said strip onto the inside wall of said tube to effect fusing of strip to tube.

10. Equipment for carrying ont the method as defined in Claim 8, wherein said means for urging said strip onto the inside of said tube includes two first rollers attached to said channel-shaped guide underneath said strip and a third roller positioned on the tube outside opposite said two rollers and spring means serving to urge said third roller onto said two rollers. - 14 - 105,745/3

11. · Equipment for carrying out the method as defined in Claim 8, wherein the means for flattening said tube Include, a first station of two spaced-apart pairs of rotating grooved rollers serving to grip said strip and the adjacent tube wall by means of said grooves in said rollers and to force the remaining portion of said tube into oblong shape positioned between straight roller portions, and a second station of two spaced-apart rollers serving for flattening said remaining tube portion and to bend it intto the plane of said strip inside said tube*

12. Equipment for carrying out the method as defined in Claim 8, wherein the means for perforating said tube in the area covering said discharge chamber includes means for conveying said flattened tube with said strip underneath a perforating tool, a centrally pivoted lever provided at its one end with a piercing tool and at its opposite end with a first roller in contact with the tube portion containing said flow restricting passages, at least one second roller supporting said flattened hose and urging it onto said roller at the lever's end, the equipment serving to pierce said tube by tilting motion of said lever about its pivot effected by said knob or bulge lifting said first roller by widening the distance between said first and said second roller.

13. The drip irrigation pipe as defined in Claim 1, wherein said discharge chamber is provided with at least one upstanding pin serving to support said tube wall during its perforation by said piercing tool.

14. The equipment as defined in Claim 12, wherein said piercing tool is a flat pointed knife. - 15 - 105,745/3

15. The equipment as defined In Claim 12, whwreln eald piercing tool Is a rotating saw.

16. The equipment as defined In Claim 12, wherein said piercing tool is a trapenning drill.

17. The drip irrigation pipe as defined in one of the Claims 1 through 3 and substantially as hereinbefore described and illustrated in the accompanying drawings.

18. The method of manufacturing the drip irrigation pipe as defined in Claims 4 or B^, and substantially as hereinbefore described.

19. The equipment for manufacture of the drip irrigation pipe as defined in one ot the Claims 5 6,7, and 9 through 16, and substantially as herein before described and illustrated In the accompanying drawings. FOR THE APPLICANTS, E.Ajjk6LUCKSMAN, PATENT ATTORNEY.