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WO1996005955A1 - Appareil permettant de fabriquer des tuyaux poreux souples - Google Patents

Appareil permettant de fabriquer des tuyaux poreux souples Download PDF

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Publication number
WO1996005955A1
WO1996005955A1 PCT/US1994/009528 US9409528W WO9605955A1 WO 1996005955 A1 WO1996005955 A1 WO 1996005955A1 US 9409528 W US9409528 W US 9409528W WO 9605955 A1 WO9605955 A1 WO 9605955A1
Authority
WO
WIPO (PCT)
Prior art keywords
extruder
feed
blended mixture
pipes
level
Prior art date
Application number
PCT/US1994/009528
Other languages
English (en)
Inventor
Henry W. Sullivan
Charles R. Killian
Paul D. Bettencourt
Original Assignee
Sullivan Henry W
Killian Charles R
Bettencourt Paul D
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US07/893,386 priority Critical patent/US5366365A/en
Priority claimed from US07/893,386 external-priority patent/US5366365A/en
Application filed by Sullivan Henry W, Killian Charles R, Bettencourt Paul D filed Critical Sullivan Henry W
Priority to AU78685/94A priority patent/AU7868594A/en
Priority to PCT/US1994/009528 priority patent/WO1996005955A1/fr
Publication of WO1996005955A1 publication Critical patent/WO1996005955A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/375—Plasticisers, homogenisers or feeders comprising two or more stages
    • B29C48/385—Plasticisers, homogenisers or feeders comprising two or more stages using two or more serially arranged screws in separate barrels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/92—Measuring, controlling or regulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/92514—Pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/92523—Force; Tension
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/9258—Velocity
    • B29C2948/926—Flow or feed rate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/92704—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92819—Location or phase of control
    • B29C2948/92857—Extrusion unit
    • B29C2948/92866—Inlet shaft or slot, e.g. passive hopper; Injector, e.g. injector nozzle on barrel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92819—Location or phase of control
    • B29C2948/92857—Extrusion unit
    • B29C2948/92876—Feeding, melting, plasticising or pumping zones, e.g. the melt itself
    • B29C2948/92895—Barrel or housing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92819—Location or phase of control
    • B29C2948/92923—Calibration, after-treatment or cooling zone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/285—Feeding the extrusion material to the extruder
    • B29C48/29—Feeding the extrusion material to the extruder in liquid form

Definitions

  • This invention relates to porous flexible pipes of controlled porosity; more particularly, this invention relates to porous flexible pipes produced by an extrusion molding process from raw materials comprising thermoset particles and thermoplastic particles, under a compaction free and segregation free process to insure a uniform quality and rheological characteristics of the final product.
  • Porous pipe has been used in underground irrigation systems.
  • Underground irrigation using porous pipes have numerous advantages over above-ground watering.
  • the water In above-ground watering, the water must enter the soil and penetrate through the root zone to benefit plants.
  • above-ground watering water can be lost through evaporation and runoff.
  • underground irrigation systems water is pumped through porous pipes and is delivered directly to the subsurface roots of the crop being cultivated.
  • nourishing fertilizer can be added to the feed water with minimum loss due to runoff.
  • air, herbicides, and/cr insecticides can be directly distributed to the subsurface root zone on the soil using underground irrigation. Because the nutrients or other chemicals are directly distributed to the roots, instead of the soil surface, less chemicals are wasted and chemical requirements are minimized.
  • Porous flexible pipes of controlled and different porosity have also been used to diffuse fine bubbles of air and/or other gases into water and/or other liquids for use in effluent treating, bioremediation and fish farming.
  • Porous pipes used for underground irrigation processes usually are made from an extrusion process employing ground rubber crumbs and polyethylene particles as raw materials.
  • U.S. Patents Nos. 4,003,408; 4,110,420; and 4,168,799 issued to Turner disclosed porous irrigation pipes produced from reclaimed rubber mixed with polyethylene as a binder.
  • the materials disclosed therein are incorporated herein by reference.
  • the prescribed mixture is extruded by a wave screw.
  • the extruder is equipped with a heating system to melt the thermoplastic polyethylene binder. During the heating and extruding process in the extruder, water vapor and any other gaseous components contained in the feed material expand to create porosity in the extrudate.
  • the extruded pipe is cooled in a water bath to preserve its final form as a porous pipe.
  • a venting capability is provided in the extruder to provide various degrees of vacuum and control the porosity of the end product porous pipe.
  • the main object of this invention is to provide a porous flexible pipe made of a thermoset material and a thermoplastic material whose composition is consistently and substantially equal to the feed composition to insure a controlled porosity.
  • Another object of the invention is to provide a porous flexible pipe of controlled pore size by introducing into a die extruder a blended mixture comprising a thermoset material such as rubber crumbs and a thermoplastic material such as polyethylene particles, wherein the same feed composition is maintained throughout the entire process by eliminating the possibility of feed segregation and compaction.
  • Yet another object of the present invention is to provide porous flexible pipes of varying but controlled porosity from the aforementioned process by varying the process variables such as the amounting of tension exert on the pipe after the extruder, and/or the temperature and pressure in the extruder.
  • Yet another object of the present invention is to provide porous flexible pipes of varying but controlled porosity from the aforementioned process which further includes a computer in cooperation with a plurality of control means to simultaneously adjust process parameters such as post-extrusion tension, and temperature and/or pressure inside the extruder barrel.
  • Flexible porous pipes can be made by extruding a mixture of thermoplastic material such as polyethylene and thermoset materials such as prevulcanized rubber crumbs through a die extruder. The mixture is heated in the extruder. While the thermoset material such as rubber crumbs are not materially affected by the heating process, the thermoplastic component of the mixture will either melt or soften sufficiently to form a binder matrix surrounding the thermoset particles. During the heating process, the gaseous components, including the water vapor vaporized from the moisture that was initially attached to the surface of the input particles, expand and form void spaces. The soft porous pipe extruded from the extruder is quickly cooled to retain the voidage contained therein. Such voidage provides porosity of the final product.
  • thermoplastic material such as polyethylene
  • thermoset materials such as prevulcanized rubber crumbs
  • porosity and "pore size” are given a broader meaning than their ordinary definition.
  • porosity or pore size means a flow ability index which is directly related to, or proportioned to, the so-called Darcy permeability utilized in the description of flow through porous media under a pressure gradient.
  • the porosity or pore size often is a function of pressure.
  • the pressure differential between the interior and exterior of the pipe it may be required that the pressure differential between the interior and exterior of the pipe be greater than a certain "threshold" value before fluid can leak through the pipe wall. Therefore, the porous pipes described in the present invention can be non-porous under one set of flowing conditions and porous under another set of flow conditions.
  • the porosity or pore size used in this disclosure can also be taken to mean the inverse of such threshold pressure.
  • the porosity and other physical characteristics, such as strength of the porous pipe are determined by the composition of pipe material and the exterior dimensions such as pipe diameter, wall thickness, etc. Most of the thermoset materials are quite compactible. This is especially true if prevulcanized rubber crumbs are used in the making of the pipes. Also, the thermoplastic feed stock such as polyethylene particles and thermoset rubber crumbs have quite different physical characteristics. They tend to segregate and cause the composition in the extruder to deviate from the desired feed composition. Such compaction and feed segregation problems can cause a wide variation in the porosity and other properties of the porous flexible pipes.
  • the feed streams comprising the thermoplastic polyethylene particles and the thermoset rubber crumbs are thoroughly blended after they are fed into the manufacturing system. This is the first step to insure the uniformity of the feed composition. Furthermore, a segregation- free solid delivery process is provided between the blender and the extruder to prevent any feed segregation, thereby to further insure that the composition of the feed stream entering the extruder is the same as the original feed. Compaction of the feed material usually occurs in a hopper attached to and before the extruder. In the present invention, a level control means is installed in the hopper to insure that the feed in the hopper is maintained under a constant extent of compaction, or even free of compaction. This is also an important step to insure not only that the porous flexible pipes are made from a mixture of thermoset and thermoplastic materials of uniform composition, but that the composition is substantially the same as the designed value to provide controlled porosity.
  • One of the advantages of having an apparatus that is competent of providing porous flexible pipes having controlled porosity as described hereinabove is that it enables the automation of the manufacturing process to produce porous pipes of pre-calculated designed porosity and desired strength.
  • the property, including porosity, of the porous pipes is affected by the feed composition, temperature and/or pressure in the extruder, and the post-extrusion tension. Adjustment of pipe property often requires simultaneous adjustments of more than one of such process parameters.
  • such automation was not available due to the lack of control over the feed composition in the extruder.
  • the manufacturing engineer knows exactly what the feed composition is inside the extruder. Therefore, the entire manufacturing process can preferably be automated or computer controlled. The manufacturing engineer can issue a simple command which would automatically change the required process parameters to produce porous pipes of desired porosity and strength.
  • Figure 1 shows a flow chart diagram of a preferred embodiment of the present invention.
  • FIG. 1 is a schematic flow chart showing a preferred embodiment of the present invention, first shows two feed streams, one containing thermoplastic material such as polyethylene particles 20 and the other containing thermoset material such as prevulcanized rubber crumbs 30.
  • a relatively unbranched low density polyethylene be used as the thermoplastic feed.
  • Such a low density linear polyethylene has a crystallinity of about 50 percent.
  • a true specific gravity between 0.90 and 0.95 is preferred.
  • a true specific gravity between 0.91 and 0.93 is further preferred.
  • Many other thermoplastic materials such as branched polyethylene, high density polyethylene, polypropylene, polyvinylchloride, poly (vinyl alcohol) , etc. , can be used.
  • thermoset feed 30 which is introduced as small particles, is basically a filler material. It should stand a high temperature and would not be materially affected during the subsequent heating process.
  • a preferred thermoset feed material is prevulcanized rubber crumbs, which can be obtained from used tires and/or other recycled rubber products. Typically, the size of the thermoset material is maintained below l/16th of an inch. It should be noted that the size of the rubber crumbs can greatly effect the porosity and the strength of the final product.
  • the two streams of feed materials are first introduced into a blender 40. This can be done with a batch process.
  • the weigh scale 41 can be used to measure the amount of respective feed streams to be added to the blender 40.
  • the blender 40 contains a blending device, such as a rake, to thoroughly mix the feed streams therein to form a homogeneously blended solid mixture.
  • the blended mixture exits the blender through a slit 42 or any other suitable means and into a feed hopper 51.
  • the slit may contain a gate means 43 to open and close the slit or to adjust the rate at which the blended mixture can exit the blender 40.
  • a level controller 54 is placed in the hopper.
  • the level controller comprises a level monitoring device 55, which can be a photo diode or an infrared level sensing device.
  • the sensing device 55 When the level of the particles in the hopper reaches a certain level, the sensing device 55 will send a signal to a controller 54, which in turn will close or reduce the gate size 43 of the slit 42 to stop or reduce the rate of the blended mixture from the blender.
  • Feed mixture from the blender is then fed to a screw conveyor 60.
  • the screw conveyor 60 which is driven by a motor 61, has small clearance to avoid any segregation of the two feed components during the feed transport process.
  • the low clearance screw conveyor 60 transports the blended mixture into another hopper, an extruder hopper 71, which is mounted immediately before the extruder barrel 70.
  • a level controlling 72 means is placed in the extruder hopper 71 to maintain a constant level of the blended mixture therein.
  • the level of the blended mixture reaches a certain level in the extruder hopper 71, as detected by a sensing means 73, it will send a signal to stop or slow down the rate of the screw conveyor.
  • the total control system can be cascaded to maintain uniformity over a range of operating inputs.
  • the blended mixture then exits the extruder hopper 71 and is fed into an extruder 70.
  • the extruder 70 used here is a typical screw extruder driven by a motor 74 for wavy movement of blended mixture therein.
  • the extruder 70 is provided with heating means to supply heat to the blended mixture. The temperature inside the extruder is maintained in such a manner so that the thermoplastic portion of the feed mixture will either melt or soften, while the thermoset component is relatively unaffected.
  • An extruder 70 to be used to practice the invention typically is equipped with a drive motor 74, which drives the wave screw inside the extruder cylinder 70 through a gear drive chain not shown.
  • the extruder 70 may also be provided with a cooling means to maintain a constant temperature environment. Further, the extruder 70 can be divided into separate temperature zones, each maintaining a separate temperature.
  • the temperature in the extruder 70 is preferably maintained within a range between 250 to 350 degrees Fahrenheit, or preferably around 300 degrees Fahrenheit.
  • the melted or softened thermoplastic material will form a coating around the thermoset particles.
  • the thermoplastic material actually acts as a binder to bind the thermoset particles together in the final product.
  • the feed particles When the feed mixture is fed into the extruder 70, the feed particles contain a certain amount of moisture and some gaseous components. The moisture will vaporize and expand in volume due to the heating action in the extruder 70 and create void spaces in the melted or softened mixture. The softened or melted mixture containing such void spaces is forced through an extruder die head 82 to form a hollow pipe.
  • the extruder die head 82 provides a constriction in the effective cross-sectional area of the extruder cylinder 70 and causes the pressure to build up within the extruder cylinder 70.
  • a heating or cooling means, or combination thereof, may be provided in the extruder die head 82 for further temperature control.
  • the extruded pipe is cooled quickly in a cooling means 90 such as a water bath, to make the final product.
  • a cooling means 90 such as a water bath
  • the temperature in the cold water bath is maintained at about 60 degrees Fahrenheit.
  • a post extrusion tension device 96 in conjunction with reel pipe coiler 91 driven by a set of gears is placed after the water bath to apply a controllable tension upon the final produced pipe to further insure a controlled constant porosity of the final porous pipe fabricate.
  • controllers 92, 93, 94 are provided, respectively, for the reel pipe coiler 91 in conjunction with a post extrusion tension device 96 for controlling the tension exerted therefrom, and the extruder for controlling the temperature and pressure therein.
  • Each of these controllers can be connected to a computer 95 via a digital/analog converter to receive command therefrom.
  • a group of process parameters can be stored in the computer, each set corresponding to a specific porosity, or a certain combination of porosity/strength.
  • the process parameters can be set at low tension, low temperature and high pressure.
  • the process parameters can be set at high tension, high temperature and low pressure.
  • a code can be assigned to each set of parameters. To produce a length of porous pipes of pre-determined quality, the operator simply enters a code or presses a button, the computer will issue a series of commands to adjust the proper tension, pressure and temperature to produce the desired product via the digital/analog converter and controller combinations. Such an automation is not possible with the prior processes due to the lack of control of the feed composition inside the extruder.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

Appareil permettant de fabriquer des tuyaux poreux souples à partir de deux courants d'alimentation contenant un matériau thermoplastique et un matériau thermodurcissable, dans lequel les courants d'alimentation sont acheminés par une transporteuse à vis sans fin (60) vers une extrudeuse (70) via une trémie (71) d'extrudeuse pratiquement sans compactage ni séparation pour garantir que la composition du courant d'alimentation dans l'extrudeuse sera pratiquement identique à la composition d'alimentation initiale. Ledit appareil peut être commandé par un ordinateur (95) si bien qu'un opérateur peut fabriquer des tuyaux présentant une porosité désirée ainsi que d'autres caractéristiques mécaniques et rhéologiques en entrant simplement une commande qui règle simultanément les paramètres de processus tels que la température et/ou la pression à l'intérieur de l'extrudeuse, et la tension post-extrusion pour répondre à un besoin spécifique.
PCT/US1994/009528 1992-06-04 1994-08-24 Appareil permettant de fabriquer des tuyaux poreux souples WO1996005955A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US07/893,386 US5366365A (en) 1992-06-04 1992-06-04 Means for controlling feedstock compaction in forming flexible porous pipes of controlled pore size
AU78685/94A AU7868594A (en) 1992-06-04 1994-08-24 Apparatus for manufacturing flexible porous pipe
PCT/US1994/009528 WO1996005955A1 (fr) 1992-06-04 1994-08-24 Appareil permettant de fabriquer des tuyaux poreux souples

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US07/893,386 US5366365A (en) 1992-06-04 1992-06-04 Means for controlling feedstock compaction in forming flexible porous pipes of controlled pore size
PCT/US1994/009528 WO1996005955A1 (fr) 1992-06-04 1994-08-24 Appareil permettant de fabriquer des tuyaux poreux souples

Publications (1)

Publication Number Publication Date
WO1996005955A1 true WO1996005955A1 (fr) 1996-02-29

Family

ID=26788384

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1994/009528 WO1996005955A1 (fr) 1992-06-04 1994-08-24 Appareil permettant de fabriquer des tuyaux poreux souples

Country Status (1)

Country Link
WO (1) WO1996005955A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012097829A1 (fr) * 2011-01-17 2012-07-26 Osmo-Drain Sales & Marketing Ag Procédé et dispositif pour fabriquer un tuyau flexible poreux

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2568332A (en) * 1946-04-15 1951-09-18 Nat Plastic Products Company Device controlling flow of material into a hopper, responsive to material level in said hopper
US4003408A (en) * 1974-02-26 1977-01-18 George C. Ballas, trustee Underground irrigation porous pipe
US4197070A (en) * 1978-08-03 1980-04-08 Owens-Illinois, Inc. Apparatus for controlling a plastic extruder
US4517316A (en) * 1984-01-24 1985-05-14 Dasurat Enterprises Pte Ltd. Porous irrigation pipe prepared from particulate elastomer and thermoplastic binder containing controlled moisture content
US4615642A (en) * 1984-10-01 1986-10-07 Dasurat Enterprises Pte Ltd. Variable porosity irrigation pipe
US4784595A (en) * 1986-09-03 1988-11-15 Reifenhauser Gmbh & Co. Maschinenfabrik Apparatus for extrusion of a thermoplastic material
US4931236A (en) * 1989-03-10 1990-06-05 Seibolt Hettinga Method for forming irrigation pipe having a porous side wall
US4958770A (en) * 1989-05-03 1990-09-25 Prescision Porous Pipe, Inc. Process for making uniform porosity flexible irrigation pipe
US4970043A (en) * 1988-04-12 1990-11-13 Doan Rosetta C Process for forming thermoplastic material from granular scrap material

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2568332A (en) * 1946-04-15 1951-09-18 Nat Plastic Products Company Device controlling flow of material into a hopper, responsive to material level in said hopper
US4003408A (en) * 1974-02-26 1977-01-18 George C. Ballas, trustee Underground irrigation porous pipe
US4110420A (en) * 1974-02-26 1978-08-29 Cry Baby, Inc. Method for extruding porous irrigation pipe
US4197070A (en) * 1978-08-03 1980-04-08 Owens-Illinois, Inc. Apparatus for controlling a plastic extruder
US4517316A (en) * 1984-01-24 1985-05-14 Dasurat Enterprises Pte Ltd. Porous irrigation pipe prepared from particulate elastomer and thermoplastic binder containing controlled moisture content
US4615642A (en) * 1984-10-01 1986-10-07 Dasurat Enterprises Pte Ltd. Variable porosity irrigation pipe
US4784595A (en) * 1986-09-03 1988-11-15 Reifenhauser Gmbh & Co. Maschinenfabrik Apparatus for extrusion of a thermoplastic material
US4970043A (en) * 1988-04-12 1990-11-13 Doan Rosetta C Process for forming thermoplastic material from granular scrap material
US4931236A (en) * 1989-03-10 1990-06-05 Seibolt Hettinga Method for forming irrigation pipe having a porous side wall
US4958770A (en) * 1989-05-03 1990-09-25 Prescision Porous Pipe, Inc. Process for making uniform porosity flexible irrigation pipe

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012097829A1 (fr) * 2011-01-17 2012-07-26 Osmo-Drain Sales & Marketing Ag Procédé et dispositif pour fabriquer un tuyau flexible poreux

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