Classifications

• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
  • A01G25/00—Watering gardens, fields, sports grounds or the like
  • A01G25/06—Watering arrangements making use of perforated pipe-lines located in the soil
• • 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
  • B29C48/355—Conveyors for extruded articles
• • 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
  • B29C48/001—Combinations of extrusion moulding with other shaping operations
  • B29C48/0012—Combinations of extrusion moulding with other shaping operations combined with shaping by internal pressure generated in the material, e.g. foaming
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2023/00—Tubular articles
  • B29L2023/003—Tubular articles having irregular or rough surfaces

Definitions

• the present invention relates to a method of manufacturing a porous pipe, such a pipe being intended in particular for the irrigation of cultivated land.
• the irrigation of cultivated land using porous buried pipes has known advantages, in comparison in particular with surface watering: water is brought in the vicinity of the roots of the plants; less water is necessary because it is not subject to the phenomenon of evaporation; the installation does not clutter the surface of the ground and this is suitable when, for example, the ground receives a lawn of games or pleasure.
• the porous pipes used must be flexible enough to follow the shapes of the ground and rigid enough transversely, that is to say according to their section, so that they do not collapse and keep in shape the passage of the water d irrigation inside the pipe all along it.
• Such porous pipes are known; thus, for example, US-A-4,958,770 describes a process for manufacturing a porous pipe intended for irrigation, comprising the steps consisting in a) preparing a homogeneous mixture composed of particles of vulcanized rubber and particles of a thermoplastic binder; b) passing said mixture through an extruder in which it is heated; c) removing said mixture from the extruder through a die in the form of a pipe; d) immerse said pipe, at the outlet of the die, in a cooling bath; e) passing the hose, at the outlet of the cooling bath, between two pulling wheels; f) wind the hose on a reel at the outlet of the pulling wheels.
• the quality of the irrigation obtained by a porous pipe of this type depends on the porosity of the pipe and, above all, on the homogeneity of this porosity throughout the pipe, to avoid that certain roots are less supplied with water. than others, see very little or no power.
• the method according to US-A-4 958 770 provides for using in step a) particles free of moisture, otherwise particles whose moisture content is less than 0.15% by weight, and extract the pipe according to step e) at a linear extraction speed equal to the linear extrusion speed according to step c), the extruder being without air intake.
• the binder melts and coats the vulcanized rubber particles which will then be assembled by bonding with the binder; this bonding will be all the less intimate and complete as an even greater force is applied to the pipe at the outlet of the cooling bath by the drawing wheels of step e); it is this more or less intimate, more or less complete bonding, which ensures the desired porosity of the pipe.
• the proportion of the mixture that is to say the relative percentages of vulcanized rubber and binder
• the linear extrusion speed and the linear extraction speed the linear extrusion speed and the linear extraction speed
• the geometric characteristics of the pipe namely its internal diameter and its radial thickness
• the temperature of the barrel of the extruder the temperature of the cooling bath.
• the method according to US-A-4 958 770 may well be suitable for producing a given pipe, of well defined geometric characteristics, but is not suitable for the production of a range of pipes; in addition, all the parameters other than the speed must be regulated in a very fine manner, which leads to a high cost price of the pipe.
• FR-A-2 693 401 also describes a method of the above type, in which the extraction speed is equal to 120% of the extrusion speed and which has the same drawbacks.
• the Applicant has discovered that taking into account the temperatures, the extruder and the cooling bath, in a simple and effective manner, could be carried out taking into account the linear contraction Ct of the pipe in the bath cooling, this contraction acting in the direction of the traction exerted on the pipe during the extraction, traction generally obtained by the difference of the linear extraction and extrusion speeds.
• a method of manufacturing a porous pipe intended for irrigation comprising the steps consisting in a) preparing a homogeneous mixture composed of particles of vulcanized rubber and particles of a thermoplastic binder; b) passing said mixture through an extruder in which it is heated; c) removing said mixture from the extruder through a die, at a linear extrusion speed W ⁇ , in the form of a pipe; d) immerse said pipe, at the outlet of the die, in a cooling bath in which said pipe is the seat of a linear contraction C expressed in percent; e) passing the pipe, at the outlet of the cooling bath, between two drawing wheels, at a linear extraction speed V2; f) wind the hose on a reel at the outlet of the pulling wheels; is characterized by the fact that Vj, V2, Ct are linked by the equation
• the mixture of step a) may contain a stabilizer.
• the mixture of step a) may contain 55 to 70% by weight of vulcanized rubber; the thermoplastic binder is preferably linear low density polyethylene.
• the vulcanized rubber particles have a particle size between 300 and 600 microns, and preferably between 400 and 500 microns; the particles of the thermoplastic binder have a particle size between 350 and 1200 microns, and preferably between 650 and 850 microns. It is preferable that during step b) the mixture is kept in the extruder at a temperature between 90 and 150 ° C; advantageously, the extruder is divided longitudinally into zones in which the temperature is kept constant, the temperature of the zones increasing from the zone close to the introduction of the mixture into the extruder to the zone situated directly before the head of the extruder from which the pipe is extracted, the temperature of the head being lower than that of the latter zone.
• the temperature of the cooling bath according to step d) is between 5 and 20 ° C, preferably between 10 and 20 ° C.
• vulcanized rubber is obtained by recovering the treads of used tires, or complete used tires.
• the invention also relates to a porous pipe obtained by the process defined above, as well as the use of such a pipe for the irrigation of cultivated land, said porous pipe being buried, in which the pipe is supplied with water under a pressure at least equal to 5 meters of water.
• FIG. 1 is a general diagram showing an example of installation for implementing the method according to the invention
• FIG. 2 is an exploded sectional view showing the main components of the head of the extruder of Figure 1;
• Figure 4 is a detail, on a larger scale, of Figure 3;
• FIG. 5 is a view along V-V of Figure 4.
• FIG. 6 is a view along VI-VI of Figure 2;
• - Figure 7 is a view along VII- VII of Figure 2;
• FIG. 8 is a section along VIII-VIII of Figure 1 - Figure 9 is a partial sectional view of a pipe obtained by the method according to the invention.
• the installation for implementing the method according to the invention, comprises two chutes 10, 11 for supplying the constituents of the mixture, namely, respectively, the vulcanized rubber in the form of particles and the thermoplastic binder, also in the form of particles.
• a feed pump 14 comprises two suction ducts 15, 16 connected to reservoirs 17, 18 each containing one of the two constituents of the mixture to be produced, and two discharge ducts 12, 13 for feeding the troughs 10 , 11 themselves supplying a mixer 9 using a pre-adjusted screw with constant dosage; the mixer 9, fixed directly to the upper part of a hopper 20, supplies the hopper 20 with constituents for the supply, in mixture 21, of the extruder 30; the homogeneity of the mixture 21, in the proportions defined above, is ensured by a mixer 19 with a vertical axis; the level 22 of the mixture in the hopper 20 is adjusted to a constant value: this is obtained by means of a level detector 22, not shown, which controls the opening of the mixer flap 9 also provided with a level detector allowing calling up the constituents of the mixture for recharging the mixer 9 when its hatch is closed after the hopper 20 has been fed; this arrangement prevents variations in the static pressure due to the mixture 21 in the hopper 20 from disturbing the extrusion conditions.
• the extruder 30 comprises a barrel 36 of horizontal axis in which is mounted for rotation an extrusion screw 31 rotatable by a motor 33; the barrel 36 is surrounded by boxes 32 distributed longitudinally defining temperature regulation zones, which is maintained at desired values by means of electric heating and air blast cooling, not shown.
• the head 40 of the extruder 30 has two heating zones, by electrical collars, and cooling by air ventilation for regulating its temperature; the temperature of the head 40 is thus maintained at a practically constant temperature, between 85 and 10 ° C.
• the pipe 23, leaving the head 40 at a linear speed Vj is immersed in a tray 34 containing a coolant 35, such as water for example.
• a coolant 35 such as water for example.
• the pipe 23 is pulled out of the tank 34, at a linear speed V2, by an extractor 24 consisting of two pulling wheels 27, 28 in the form of grooved pulleys whose section is semi-circular; the grooves are bordered by two circular lateral tracks, two tracks 37 for the pulling wheel 27, and two tracks 38 for the pulling wheel 28; the two pulling wheels 27, 28 roll one on the other via the circular tracks 37, 38 so that a circular passage 29 (FIG. 7) is defined, the pipe 23 passing through the passage 29 with a slight tightening to obtain the draft of pipe 23 at speed V2; the pipe 23 is then wound on a reel 25.
• an extractor 24 consisting of two pulling wheels 27, 28 in the form of grooved pulleys whose section is semi-circular; the grooves are bordered by two circular lateral tracks, two tracks 37 for the pulling wheel 27, and two tracks 38 for the pulling wheel 28; the two pulling wheels 27, 28 roll one on the other via the circular tracks 37, 38 so that a circular passage 29 (FIG. 7) is defined,
• the head 40 of the extruder 30, better visible in FIGS. 2 to 7, comprises on the side of the barrel 36 of the extruder a compression stage and on the opposite side a shaping stage;
• the compression stage consists of a housing 41 crossed by a frustoconical axial passage 68 whose small base is located on the side of the connection of the housing 41 to the barrel 36 of the extruder, a fixing flange 62 being provided for this effect, provided with fixing holes 61;
• the shaping stage comprises a hollow die support 43 provided at the end with a threaded bore 66 in which is mounted by screwing the sleeve 65 externally threaded with a die 44 for shaping the pipe;
• the bore 66 communicates with a cylindrical bore of smaller diameter from which extends a frustoconical passage 67;
• the sleeve 65 of the die 44 is extended externally, on the right with respect to the figures, by a tail 56 whose outer surface has a square section to facilitate the operation of screwing the
• the housing 41 of the compression stage and the support 43 of the shaping stage are assembled by means of a flange 42, in the general form of a disc, provided with an anti-turbulence device; the housing 41 is provided with a flange 63 in which are provided fixing holes 60 which cooperate with corresponding fixing holes 60 provided in the flange 42; similarly, the support 43 is provided with a flange 64 in which are provided fixing holes 76 which cooperate with corresponding fixing holes 76 provided in the flange 42 visible in FIG. 6.
• the flange 42 is traversed by a bore 59 cylindrical axial internally threaded; the bore 59 is intended for mounting by screwing, on the one hand, on the side of the casing 41 of a compression cone 51, and, on the other hand, on the side of the die support 43 of a punch support 53 ; to do this, the compression cone 51 and the support 53 are provided with circular bases, respectively 57 and 58, externally threaded, their threads corresponding to that of the bore 59 of the flange 42.
• the base 57 carries a cone 69 whose base is of a diameter slightly greater than that of the base 57 and defines an annular contact surface with the transverse face opposite the flange 42; the base 58 extends along a cylindrical part 77 with a diameter slightly greater than that of the base 58 also defining an annular contact surface with the transverse face opposite the flange 42; the cylindrical part 77 serves as the base for a truncated cone 55, the small base of which extends along a cylindrical end piece 56 of the same diameter; when the casing 41 and the flange 42 are assembled, as shown in FIG.
• the frustoconical passage 68 and the cone 69 define between them an annular channel whose section decreases towards the flange 42, the inclination on the axis of the passage 68 being less than the half-angle at the top of the cone 69, so that the mixture is subjected to compression there.
• the tip 56 of the support 53 is provided with an internally threaded cylindrical bore which receives, as shown in Figure 4, a threaded rod 50 whose length is greater than the axial length of said bore; the part of the threaded rod 50 which protrudes from said bore is used for mounting by screwing a punch 54 whose end cylindrical 49 is provided with an internally threaded bore at the pitch of the threaded rod 50; the cylindrical end 49 is provided with a collar 74 having radial slots 75 (FIG.
• the angle at the top of the truncated cone 48 is less than that of the frustoconical channel 45 so that the cross section of the passage defined between the truncated cone 48 and the frustoconical channel 45 decreases towards the exit of the die 44.
• the radial space formed between the cylindrical channel 46 of the die 44 and the cylinder 47 of the punch 54 makes it possible to define the desired thickness E of the pipe 23, the outside diameter of the cylinder 47 defining the inside diameter D of the pipe 23 ( Figure 8): there are several sets of die 44 and punch 54 adapted to different desired values of E and D.
• the sum of the axial heights of the bases 57, 58 is less than the axial length of the bore 59 of the flange 42 so that a chamber 74 is defined; the flange 42 is pierced with radial channels 70 ( Figure 6) communicating said chamber 74 with the outside; the flange 42 has axial passages 52 distributed circumferentially, in the form of arcs of a circle, allowing the mixture to pass through the flange 42 from the compression stage 41-51 to the shaping stage 43-44-54.
• the support 53, the threaded rod 50 and the punch 54 are provided with a central channel respectively 71, 72, 73 of small diameter, of the order of five millimeters for example, so that, when the head 40 is assembled, a channel 71-72-73 connects room 74 with the outside, at the exit of the punch 54; the role of channel 71-72-73 will appear below.
• the frustoconical passage 68 has an axial length of 200 mm, the diameters of the bases being 50 and 100 mm; the cone 69 has a length of 110 mm and a base of 70 mm in diameter; the cylindrical part 77, the truncated cone 55 and the end piece 56 have lengths of 40 mm, 100 mm and 20 mm respectively, while the diameters of the cylindrical part 77 and the end piece 56 are respectively 70 and 25 mm; the frustoconical passage 67 of the support 43 has a length of 125 mm and bases whose diameters are 110 mm and 30 mm.
• the punch 54 has a cylindrical end 49, a truncated cone 48 and a cylinder 47 whose axial length is respectively 20 mm, 25 mm, 60 mm, the bases of the truncated cone 48 having a diameter of 20 mm and 16 mm; the frustoconical channel 45 of the die 44 has an axial height of 40 mm and the bases of the diameters of 45 mm and 22 mm, the axial length of the cylindrical channel 46 being 60 mm.
• the vulcanized rubber can be of any type; for economic reasons, it is preferable to grind used used tires, in particular their treads; the size of the particles of ground rubber is between 300 and 600 microns, better still between 400 and 500 microns.
• the thermoplastic binder can also be of any type, but polyethylene is preferred, in particular linear low density polyethylene, the density of which is of the order of 0.9 g / cm 3 .
• the mixture produced contains between 55 and 70, by weight, of vulcanized rubber, the corresponding proportion of polyethylene being from 45 to 30%; the mixture contains only rubber and binder; indeed, low density linear polyethylene has the advantage that its chains are not destroyed under the conditions of the extrusion operation; of course, if another binder is used, it is possible, in some cases, to add to the mixture a stabilizer avoiding the destruction of the chains of the thermoplastic binder.
• the level 22 of this mixture in the hopper 20 is regulated; experience has shown that regulating the level 22 at a height of plus or minus 10 cm is sufficient not to disturb the extrusion conditions, the total height of the hopper 20 being of the order of 80 cm to 100 cm.
• FIG 1 there are shown three boxes 32 defining temperature regulation zones of the barrel 36; alternatively, there are four boxes 32.
• the regulated temperatures range from 90 to 150 ° C; it increases from the zone close to the hopper 20 to the zone close to the head 40 of the extruder; 140 ° C higher instead of 150 ° C has also worked well in some cases.
• Two temperature regulation zones are provided for the head 40 of the extruder, said temperature being lower than those of the barrel 36.
• FIG. 9 shows in section, partially, a pipe 23 consisting of particles of vulcanized rubber covered with polyethylene and more or less agglomerated, shown on a large scale, the pipe 23 having an internal diameter D and a radial thickness E.
• the linear extrusion speed Vj used is between 400 and 1000; it is chosen according to D and E desired: for example, if D is 13 mm and E of 2 mm, it is of the order of 500 meters per hour, the proportion of rubber in the mixture being l 65%.
• the linear extraction speed V2 is chosen, in accordance with the invention, taking into account the linear contraction Ct of the pipe in the cooling bath: according to this example, the temperature of the bath being 10 ° C, Ct is equal to 12%; V2 is chosen to be greater than 88% of Vj, ie here equal to l0% of Vj; under these conditions, the pipe 23 obtained has a uniform porosity over its entire length.
• the result according to the invention is obtained for a whole range of pipes; if we define this by the diameter D and the ratio -, the diameter D can go from 10 mm to 20 mm, see beyond, and E the ratio - can advantageously be between 5 and 7, but this E ratio can go down to 2 and go up to 10.
• the passage of the pipe 23 in the cooling bath is facilitated when the pipe 23 has a certain stiffness; if this is not the case, it is possible to blow air into the chamber 74 through the radial channels 70; the air thus blown through the duct 71-72-73 and enters the interior of the pipe 23, leaving the punch 54 and giving the pipe 23 a certain hold makes it possible to hold the value of D at the desired value; when no air is blown into the chamber 74, the duct 71-72-73 and the radial channels 70, to the atmosphere, are used for degassing.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Soil Sciences (AREA)
• Water Supply & Treatment (AREA)
• Environmental Sciences (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Molding Of Porous Articles (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9460535

Family Applications (1)

Country Status (8)

Families Citing this family (9)

Family Cites Families (6)

• 1994
  • 1994-03-01 FR FR9402320A patent/FR2716835B1/fr not_active Expired - Fee Related
• 1995
  • 1995-02-20 DE DE0697949T patent/DE697949T1/de active Pending
  • 1995-02-20 ES ES95909845T patent/ES2116949T1/es active Pending
  • 1995-02-20 AU AU18159/95A patent/AU1815995A/en not_active Abandoned
  • 1995-02-20 EP EP95909845A patent/EP0697949A1/de not_active Withdrawn
  • 1995-02-20 WO PCT/FR1995/000195 patent/WO1995023681A1/fr not_active Application Discontinuation
  • 1995-02-26 IL IL112790A patent/IL112790A/xx not_active IP Right Cessation
  • 1995-11-01 OA OA60730A patent/OA10241A/fr unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events