WO1991007269A1 - A method for manufacturing hollow tubular bodies and apparatus for carrying out the method - Google Patents

A method for manufacturing hollow tubular bodies and apparatus for carrying out the method Download PDF

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Publication number
WO1991007269A1
WO1991007269A1 PCT/SE1989/000651 SE8900651W WO9107269A1 WO 1991007269 A1 WO1991007269 A1 WO 1991007269A1 SE 8900651 W SE8900651 W SE 8900651W WO 9107269 A1 WO9107269 A1 WO 9107269A1
Authority
WO
WIPO (PCT)
Prior art keywords
core
hollow tubular
matrix
sectional shape
rotatable core
Prior art date
Application number
PCT/SE1989/000651
Other languages
French (fr)
Inventor
Curt Andersson
Original Assignee
Curt Andersson
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
Application filed by Curt Andersson filed Critical Curt Andersson
Publication of WO1991007269A1 publication Critical patent/WO1991007269A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
    • B30B11/22—Extrusion presses; Dies therefor
    • B30B11/24—Extrusion presses; Dies therefor using screws or worms
    • 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
    • B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
    • 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
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B29C48/33—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles with parts rotatable relative to each other
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/94—Lubricating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
    • B30B11/22—Extrusion presses; Dies therefor
    • B30B11/224—Extrusion chambers
    • B30B11/225—Extrusion chambers with adjustable outlet opening
    • 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
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts

Definitions

  • the present invention relates primarily to a method of manufacturing hollow tubular bodies, and particularly, but not exclusively, to a method of manufacturing hol ⁇ low tubular bodies of circular internal c.OSS- ⁇ ection from a compressible starting material.
  • a plastics material preferably in a molt, n state, is introduced into a compresion space define1 by an inner rotatable core or mandrel and an outer surrounding matrix, where the material is compressed and from where the compressed material is pressed to a further com ⁇ pression space defined between said rotatable core and said matrix where the plastics material solidifies.
  • the rotatable core functions to impart a circular, internal cross-sectional shape to the hollow tubular member.
  • the invention also relates to an apparatus for manufac ⁇ turing hollow tubular bodies from a compressible material.
  • Paper tubes or hollow cylinders can be produced b winding paper strips around a mandrel.
  • a particularly challenging technical problem also ari ⁇ ses in realizing that when the mixture comprises a filling material admixed with plastics material the hollow tubular member thus manufactured can be given a hardness equal to that of a conventionally manufactured plastic tubular member, preferably of the same wall thickness, and even a degree of hardness greater than that of a conventional plastic tube.
  • a particularly challenging technical problem also ari ⁇ ses in realizing that the aforesaid technical problem can be solved when the plastic content of the starting ⁇ ixture is compressed while in a molten state and is caused to solidify about a rotatable core.
  • a particularly challenging technical problem also ari ⁇ ses in enabling the mixture to-be compressed to a re ⁇ quisite degree with the aid of a simple screw-feeder configured with a decreasing pitch, such that the re- quisite compression is effected in the actual screw conveyor itself.
  • a particularly challenging technical problem also ari- ' - ses in the provision of a rotatable core so configured as to impart a circular shape to the internal surfaces of the tubular member under manufacture and to provide means whereby the interface between the rotatable core and the inner surface of the tubular member can be cooled and lubricated, so as to reduce the friction between said core and said tubular member.
  • a particularly challenging technical problem also ari ⁇ ses in the provision of a simple matrix for lubricating and cooling the interface between the rotatable core and the inner surface of the tubular member, such as to reduce the friction therebetween.
  • the invention thus relates primarily to a method for manufacturing hollow tubular members having an internal circular cross-sectional shape from compressible material.
  • the compressible material used comprises a mixture of filler material and plastics material, which is intro ⁇ quizd into a space defined by an internal core and an external matrix, with the plastics material preferably in a molten state, where said mixture is subjected to compression.
  • the compressed material is then pressed into a further space between the rotatable core and said matrix, where the plastics material is cooled and solidifies.
  • the rotatable core is intended to impart a circular, internal cross-section to the tubular member.
  • the rota ⁇ table core is configured with a part which has an el ⁇ liptical cross-section and which is preferably located between the end-parts of circular cross-section.
  • the diameter of the end-part facing towards the compression space has a diameter which is slightly smaller than the diameter of the end-part remote from said compression space, so that the rotatable core is able to work the interior cross-section of the tubular member and to produce a tubular member which in its solidified state will have the wall thickness desired.
  • a coolant find lubricant preferably water, is introduced between the rotatable core and the tubular memeber under manufacture.
  • the matrix i& divided into sections and means are provided for displacing the matrix sections, either synchronously or asynchronously, forwards and backwards along the external surface of the tubular member during its manufacture.
  • possibi ⁇ lities are created which permit a mixture comprising a filling material and a plastic material in a liquid state, with the plastic material being present in a smaller quantity than the filling material, and/or including a reinforcing material such as glass-fibre material to be introduced under pressure into a com ⁇ pressing device, preferably in the form of a screw- feeder, and to produce a tubular member of high mecha ⁇ nical strength and density with the aid of a simple rotatable core.
  • a com ⁇ pressing device preferably in the form of a screw- feeder
  • Frictional losses which can be very high, are signifi ⁇ cantly reduced by introducing water between the rotat ⁇ able core and the hollow tubular body during its manu ⁇ facture, and by enabling the outer walls of the matrix to be displaced during the manufacture of said body.
  • Figure 1 is a side view, partially in section, of an apparatus constructed in accordance with the invention
  • Figure 2 is a simplified sectional view taken on the line I-I in Figure 1.
  • the reference 1 in Figure 1. identifies generally a known device by means of which a plastics material can be mixed with a filler and/or a reinforcing material.
  • the device also functions to heat the plastics mate- rial, preferably to a temperature at which said mate ⁇ rial will melt.
  • the filler with which the plastics material is mixed may be paper.
  • the proportion of plastics material present will be less than 50% but preferably ⁇ bout 10%, a normal value in this respect will prefer ⁇ ably be between 20 and 30%.
  • the schematically illustrated device 1 also includes a precompressing device which functions to deliver a mix ⁇ ture of liquid plastics-material and filler under pres ⁇ sure to a space 3.
  • This space 3 is conceived to be defined by a core 4 and a surrounding, outer matrix 5.
  • the mixture delivered to said space is compressed suc ⁇ cessively and when located in the section referenced A will have a degree of compression commensurate with the compression forces exerted thereon as the mixture moves through a tubular passage 2 extending from the precom- pression device 1, and will have a much higher degree of compression when reaching the region reference B in Figure 1, although the plastics material will still be in a liquid or molten state.
  • the plastics material solidifies and is assumed to have solidified substantially when the mixture reaches the region referenced C in Figure 1.
  • the plastics material When the mixture reaches the region D in Figure 1, the plastics material will have completely solidified and the mixture will have been compressed to its final state, so as to produce a tubular body 10.
  • the compressed mixture is thus moved from the region B to a further space 6 defined by a rotatable core or mandrel 7 and the aforesaid matrix 5, where the plastic 5 content of the mixture in the region C solidifies and where the rotatable core 7 imparts an inner, circular cross-sectional shape of diameter fi to the hollow tubu ⁇ lar member 10.
  • the screw-feeder having a decreasing-pitch helix func- '15 tions to compress the mixture to a predetermined extent during its travel from the region A to the region B of the compression path.
  • the ⁇ crew-feeder comprising the inner core 4 and helix 20 8, is rotated in the same direction of rotation as the rotatable core 7 by means not shown.
  • the internal core 7 thus rotates together with the screw-feeder 4, 8, although it is proposed that the rotatable core 7 is rotated at a greater speed than the screw-feeder. 25
  • the part 7a of the rotatable core 7 located between the end-parts 7b and 7c of said core has an elliptical cross-sectional shape, whereas the said end-parts 7b and 7c will preferably have a circular cross-sectional 30 shape.
  • the diameter of the end-part 7b located nearest the compression device has a slightly smaller diameter than the end-part 7c distal from said compression device, and the pitch of the elliptical part 7a will increase continuously from the diameter of the end-part 7b to the diameter of the end-part 7c.
  • This agent will preferably be water.
  • the con- *duits 11 and 12 are used to deliver water to the space 3 and also to- remove water therefrom.
  • the core may also be configured with a pitch such that as the core rotates the tubular body under manufacture will be urged to the right and there ⁇ with reduce frictional forces.
  • Figure 2 illustrates a matrix wt.ich is divided into four sections 5a, 5b, 5c and 5d.
  • Each of these sections (for instance the section 5a) coacts with a hydraulic piston-and-cylinder device 15 by means of which a respective matrix section can be ' , moved backwards and forwards in the direction of the longitudinal axis of the hollow tubular body 10.
  • the matrix sections may be moved synchronously or asynchro ⁇ nously.
  • the matrix sections are held in position by means of rollers 16, 17 which extend along the whole of the matrix, even though Figure 1 only shows the rollers located in the region of the compression device.
  • cooling passages are provided in the matrix sections 5a, 5b, 5c and 5d in a known manner, such as to enable heat to be removed from the .fiixture located in the regions A and B of the space 3, so that * ;he plastics material will solidifiy in the region C-
  • the pistr n-cylinder device 15 acting on the matrix sections-5a, 5b, 5c and 5d (only section 5a being shown) cin be caused to move the matrix sections through short or a long distance with each stroke, and can also be controlled so that each stroke is of longer or shorter duration.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

Abstract

The invention relates to a method and an apparatus for manufacturing hollow tubular bodies having a circular, internal cross-sectional shape, from a compressible material. A mixture of plastics material and a filling material, with the plastics material preferably in a molten state, is supplied to a first space defined by an inner core or mandrel (4) and an outer matrix (5), where the mixture is subjected to compression. The compressed material (B) is pressed to a second space (6) between a rotatable core (7) and the matrix (5), where the plastics material solidifies. A part of the rotatable core (7) has an elliptical cross-sectional shape and the core (7) functions to impart a circular internal cross-sectional shape to the hollow tubular body during its manufacture.

Description

A METHOD FOR MANUFACTURING HOLLOW TUBULAR BODIES AND APPARATUS FOR CARRYING OUT THE METHOD
TECHNICAL FIELD
The present invention relates primarily to a method of manufacturing hollow tubular bodies, and particularly, but not exclusively, to a method of manufacturing hol¬ low tubular bodies of circular internal c.OSS-εection from a compressible starting material.
A plastics material, preferably in a molt, n state, is introduced into a compresion space define1 by an inner rotatable core or mandrel and an outer surrounding matrix, where the material is compressed and from where the compressed material is pressed to a further com¬ pression space defined between said rotatable core and said matrix where the plastics material solidifies. The rotatable core functions to impart a circular, internal cross-sectional shape to the hollow tubular member.
The invention also relates to an apparatus for manufac¬ turing hollow tubular bodies from a compressible material.
BACKGROUND PRIOR ART
Various methods and apparatus for the manufacture of hollow tubular bodies are known to the art, these methods and apparatus being adapted to the nature of the material from which said bodies are made.
For instance, the methods used in the manufacture of concrete tubes is normally different to the methods used in the manufacture of cast-iron tubes. Steel pipes and tubes are normally manufactured in a different manner to plastic pipes or tubes, where the latter are normally produced by extrusion.
Paper tubes or hollow cylinders can be produced b winding paper strips around a mandrel.
The use of a rotating core and a stationary nozzle in the manufacture of plastic tubes is known, for instance, from prior publications (US-A-3,611,490, and US-A-3,651,187).
Apparatus in which material is pumped with the ait' of a screw-feeder are known from each of the publications DE-A-1.778.915, GB-A-1 159 453 and GB-A-2 089 717.
SUMMARY OF THE INVENTION
TECHNICAL PROBLEMS A study of the prior art within this technical field will reveal that a particularly challenging technical problem arises in the provision of a method and an apparatus by means of which hollow tubular bodies can be manufactured continuously in a simple fashion, from a compressible mixture comprising a filling material and a plastics material, and in which the hollow tubu¬ lar member can be given a round, internal cross-sec¬ tional shape.
A particularly challenging technical problem also ari¬ ses in realizing that when the mixture comprises a filling material admixed with plastics material the hollow tubular member thus manufactured can be given a hardness equal to that of a conventionally manufactured plastic tubular member, preferably of the same wall thickness, and even a degree of hardness greater than that of a conventional plastic tube.
A particularly challenging technical problem also ari¬ ses in realizing that the aforesaid technical problem can be solved when the plastic content of the starting ώixture is compressed while in a molten state and is caused to solidify about a rotatable core.
A particularly challenging technical problem also ari¬ ses in enabling the mixture to-be compressed to a re¬ quisite degree with the aid of a simple screw-feeder configured with a decreasing pitch, such that the re- quisite compression is effected in the actual screw conveyor itself.
A particularly challenging technical problem also ari-'- ses in the provision of a rotatable core so configured as to impart a circular shape to the internal surfaces of the tubular member under manufacture and to provide means whereby the interface between the rotatable core and the inner surface of the tubular member can be cooled and lubricated, so as to reduce the friction between said core and said tubular member.
A particularly challenging technical problem also ari¬ ses in the provision of a simple matrix for lubricating and cooling the interface between the rotatable core and the inner surface of the tubular member, such as to reduce the friction therebetween.
A particularly challenging technical problem also ari¬ ses in the provision of a simple matrix configuration intended to embrace the tubular member during its manu¬ facture, and in the provision of means for reducing friction between the matrix and said tubular member, and in the provision of a matrix which is so configured that the tubular member will obtain an outer, circular cross-section central of the inner, circular cross- section. r
SOLUTION The invention thus relates primarily to a method for manufacturing hollow tubular members having an internal circular cross-sectional shape from compressible material.
The compressible material used comprises a mixture of filler material and plastics material, which is intro¬ duced into a space defined by an internal core and an external matrix, with the plastics material preferably in a molten state, where said mixture is subjected to compression. The compressed material is then pressed into a further space between the rotatable core and said matrix, where the plastics material is cooled and solidifies. The rotatable core is intended to impart a circular, internal cross-section to the tubular member.
In accordance with the present invention, the rota¬ table core is configured with a part which has an el¬ liptical cross-section and which is preferably located between the end-parts of circular cross-section.
According to one advantageous embodiment of the present invention, the diameter of the end-part facing towards the compression space has a diameter which is slightly smaller than the diameter of the end-part remote from said compression space, so that the rotatable core is able to work the interior cross-section of the tubular member and to produce a tubular member which in its solidified state will have the wall thickness desired.
For friction-reducing and cooling purposes, a coolant find lubricant, preferably water, is introduced between the rotatable core and the tubular memeber under manufacture.
According to another advantageous embodiment of the invention, the matrix i& divided into sections and means are provided for displacing the matrix sections, either synchronously or asynchronously, forwards and backwards along the external surface of the tubular member during its manufacture.
There is also provided an apparatus by means of which the method can be put into effect.
ADVANTAGES
Those advantages which may primarily be regarded as being characteristic of a method and an arrangement according to the present invention are that possibi¬ lities are created which permit a mixture comprising a filling material and a plastic material in a liquid state, with the plastic material being present in a smaller quantity than the filling material, and/or including a reinforcing material such as glass-fibre material to be introduced under pressure into a com¬ pressing device, preferably in the form of a screw- feeder, and to produce a tubular member of high mecha¬ nical strength and density with the aid of a simple rotatable core.
Frictional losses, which can be very high, are signifi¬ cantly reduced by introducing water between the rotat¬ able core and the hollow tubular body during its manu¬ facture, and by enabling the outer walls of the matrix to be displaced during the manufacture of said body.
The primary characteristic features of a method for manufacturing a hollow tubular body in accordance with the present invention are set forth in the characteriz¬ ing clause of the following Claim 1, whereas the pri¬ mary characteristic features of an apparatus for the manufacture of such hollow tubular bodies are set forth in the characterizing clause of the following Claim 6.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of an apparatus for manufactur¬ ing a hollow tubular body from compressible material will now be described in more detail with reference to the accompanying drawings, in which Figure 1 is a side view, partially in section, of an apparatus constructed in accordance with the invention; and Figure 2 is a simplified sectional view taken on the line I-I in Figure 1.
DESCRIPTION OF A NOW PREFERRED EMBODIMENT
The reference 1 in Figure 1.identifies generally a known device by means of which a plastics material can be mixed with a filler and/or a reinforcing material.
The device also functions to heat the plastics mate- rial, preferably to a temperature at which said mate¬ rial will melt.
The filler with which the plastics material is mixed may be paper. When the filler comprises cut or shredded paper and the plastics material is heated to a liquid state, it is proposed that the proportion of plastics material present will be less than 50% but preferably έbout 10%, a normal value in this respect will prefer¬ ably be between 20 and 30%.
The schematically illustrated device 1 also includes a precompressing device which functions to deliver a mix¬ ture of liquid plastics-material and filler under pres¬ sure to a space 3. This space 3 is conceived to be defined by a core 4 and a surrounding, outer matrix 5.
The mixture delivered to said space is compressed suc¬ cessively and when located in the section referenced A will have a degree of compression commensurate with the compression forces exerted thereon as the mixture moves through a tubular passage 2 extending from the precom- pression device 1, and will have a much higher degree of compression when reaching the region reference B in Figure 1, although the plastics material will still be in a liquid or molten state.
As the mixture passes through the apparatus, to the right in Figure 1, the plastics material solidifies and is assumed to have solidified substantially when the mixture reaches the region referenced C in Figure 1.
When the mixture reaches the region D in Figure 1, the plastics material will have completely solidified and the mixture will have been compressed to its final state, so as to produce a tubular body 10. The compressed mixture is thus moved from the region B to a further space 6 defined by a rotatable core or mandrel 7 and the aforesaid matrix 5, where the plastic 5 content of the mixture in the region C solidifies and where the rotatable core 7 imparts an inner, circular cross-sectional shape of diameter fi to the hollow tubu¬ lar member 10.
'10 Compression of the mixture during its movement from region A to region B is effected with the aid of a '"■'> screw-feeder the helix 8 of which has a pitch which
' decreases in a direction towards the rotatable core 7.
The screw-feeder having a decreasing-pitch helix func- '15 tions to compress the mixture to a predetermined extent during its travel from the region A to the region B of the compression path.
The εcrew-feeder, comprising the inner core 4 and helix 20 8, is rotated in the same direction of rotation as the rotatable core 7 by means not shown. The internal core 7 thus rotates together with the screw-feeder 4, 8, although it is proposed that the rotatable core 7 is rotated at a greater speed than the screw-feeder. 25
The part 7a of the rotatable core 7 located between the end-parts 7b and 7c of said core has an elliptical cross-sectional shape, whereas the said end-parts 7b and 7c will preferably have a circular cross-sectional 30 shape.
The diameter of the end-part 7b located nearest the compression device has a slightly smaller diameter than the end-part 7c distal from said compression device, and the pitch of the elliptical part 7a will increase continuously from the diameter of the end-part 7b to the diameter of the end-part 7c. Thus, there will be located between the rotatable core 7 and the inner sur- face of the hollow tubular-member under manufacture a •space 9 to which a cooling and lubricating agent can be introduced via a conduit 11 and a conduit 12 respec- €ively. This agent will preferably be water. The con- *duits 11 and 12 are used to deliver water to the space 3 and also to- remove water therefrom.
Ψhe introduction of water into said space greatly redu¬ ces the friction occurring between the core or mandrel tand the inner surface of the hollow tubular body being manufactured. The core may also be configured with a pitch such that as the core rotates the tubular body under manufacture will be urged to the right and there¬ with reduce frictional forces.
For the purpose of reducing friction between the outer surfaces of the hollow tubular member under manufacture and the outer matrix 5, it is suggested that the matrix js divided into sections. Figure 2 illustrates a matrix wt.ich is divided into four sections 5a, 5b, 5c and 5d.
Each of these sections (for instance the section 5a) coacts with a hydraulic piston-and-cylinder device 15 by means of which a respective matrix section can be', moved backwards and forwards in the direction of the longitudinal axis of the hollow tubular body 10. The matrix sections may be moved synchronously or asynchro¬ nously.
The matrix sections are held in position by means of rollers 16, 17 which extend along the whole of the matrix, even though Figure 1 only shows the rollers located in the region of the compression device.
It is also proposed that cooling passages are provided in the matrix sections 5a, 5b, 5c and 5d in a known manner, such as to enable heat to be removed from the .fiixture located in the regions A and B of the space 3, so that *;he plastics material will solidifiy in the region C-
«• The pistr n-cylinder device 15 acting on the matrix sections-5a, 5b, 5c and 5d (only section 5a being shown) cin be caused to move the matrix sections through short or a long distance with each stroke, and can also be controlled so that each stroke is of longer or shorter duration.
It will be understood, that the invention is not restricted to the aforedescribed and illustrated em¬ bodiments and that modifications can be made within the scope of the invention as defined in the following claims.

Claims

1. A method for the manufacture of hollow tubular bodies of circular internal cross-section from a com¬ pressible material, by mixing a filling material with a plastics materia , preferably in a molten state , and delivering said it.ixture to a first space defined by a rotatable core or mandrel and a matrix which embraces said core, and co'inpressing said mixture in said space, and by pressing s«.id compressed material to a second space defined between said rotatable core and said matrix, where sa5.!_i plast-fics material solidifies and said rotatable c re imparts an internal, circular cross-sectional shape to said tubular member, charac¬ terized by configuring the rotatable core with a part which has an elliptical cross-sectional shape.
2. A method according to Clai-n 1, characterized in that the end-parts of said core located on either side of said part of elliptical cross-section have a circular cross-sectional shape.
3. A method according to Claim 2, characterized in that the diameter of one said end-part lying nearest the compression device has a diameter which is slightly smaller than the diameter of the other said end-part distal from said compression device.
4. A method according to Claim 1, 2 or 3, charac¬ terized in that a coaling and lubricating agent, such as water, is introduced to the interface between the rotatable core and the hollow tubular member during the manufacture thereof.
5. A method according to Claim 1, characterized in that the matrix comprises a plurality of sections each of which can be displaced reciprocatingly along the outer surface of the hollow tubular member during its manu- facture.
6. An apparatus for the nianufacture of hollow tubular Sodies, preferably in accordance with the method defi¬ ned in any one of the preceding claims, characterized by a compression device w ich is intended for the com¬ pression of a mixture comprising liquid plastics mate¬ rial and a filling material, and comprising a rotate- able core or mandrel (7) rtiich is also intended to function as a rotatable core in a zone in which the plastics material exists In a substantially solid state, and in that a part of the rotatable core has an elliptical cross-sectional shape and is intended to work the inner surface of the hollow tubular body during its manufacture.
7. An apparatus according to Claim 6, characterized in that a multi-section matrix (5) is arranged to embrace the hollow tubular member (10) during its manufacture; and in that one or more of said matrix sections can be moved backwards and forwards.
PCT/SE1989/000651 1988-10-19 1989-11-10 A method for manufacturing hollow tubular bodies and apparatus for carrying out the method WO1991007269A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE8803737A SE461139B (en) 1988-10-19 1988-10-19 MADE TO MANUFACTURE PIPES AND DEVICE BEFORE ITS PREPARATION

Publications (1)

Publication Number Publication Date
WO1991007269A1 true WO1991007269A1 (en) 1991-05-30

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998009709A1 (en) * 1996-09-09 1998-03-12 Plymouth Products, Inc. Method and apparatus for the continuous extrusion of block elements
CN105599113A (en) * 2015-12-29 2016-05-25 浙江轩鸣新材料有限公司 Forming machine for insulating pipes

Citations (5)

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GB1159453A (en) * 1965-07-27 1969-07-23 Rexall Drug Chemical Improvements in or relating to the Extrusion of Plastics Tubing
DE1778915A1 (en) * 1968-05-28 1971-09-16 Stanniolfabrik Burgdorf Ag Device for blowing hoses made of thermoplastics
US3611490A (en) * 1968-06-28 1971-10-12 Sidel Sa Extrusion die for forming tubes
US3651187A (en) * 1969-10-16 1972-03-21 Hercules Inc Extrusion process
GB2089717A (en) * 1980-12-19 1982-06-30 Proplast Oy An extruder for manufacturing plastic pipes

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GB1159453A (en) * 1965-07-27 1969-07-23 Rexall Drug Chemical Improvements in or relating to the Extrusion of Plastics Tubing
DE1778915A1 (en) * 1968-05-28 1971-09-16 Stanniolfabrik Burgdorf Ag Device for blowing hoses made of thermoplastics
US3611490A (en) * 1968-06-28 1971-10-12 Sidel Sa Extrusion die for forming tubes
US3651187A (en) * 1969-10-16 1972-03-21 Hercules Inc Extrusion process
GB2089717A (en) * 1980-12-19 1982-06-30 Proplast Oy An extruder for manufacturing plastic pipes

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Publication number Priority date Publication date Assignee Title
WO1998009709A1 (en) * 1996-09-09 1998-03-12 Plymouth Products, Inc. Method and apparatus for the continuous extrusion of block elements
CN1079687C (en) * 1996-09-09 2002-02-27 普利茅斯产品公司 Method and apparatus for continuous extrusion of block elements
CN105599113A (en) * 2015-12-29 2016-05-25 浙江轩鸣新材料有限公司 Forming machine for insulating pipes

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SE8803737D0 (en) 1988-10-19
SE461139B (en) 1990-01-15

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