Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D23/00—Producing tubular articles
  • B29D23/001—Pipes; Pipe joints
• • 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
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/22—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of tubes
  • B29C55/24—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of tubes radial
• • 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
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/22—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of tubes
  • B29C55/26—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of tubes biaxial
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L9/00—Rigid pipes
  • F16L9/18—Double-walled pipes; Multi-channel pipes or pipe assemblies
• • 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
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
• • 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
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
  • B29K2023/06—PE, i.e. polyethylene
• • 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
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/10—Polymers of propylene
  • B29K2023/12—PP, i.e. polypropylene
• • 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
  • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
  • B29K2027/06—PVC, i.e. polyvinylchloride
• • 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
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0037—Other properties
  • B29K2995/005—Oriented
  • B29K2995/0051—Oriented mono-axially
• • 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
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0037—Other properties
  • B29K2995/005—Oriented
  • B29K2995/0053—Oriented bi-axially
• • 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
• • 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
  • B29L2024/00—Articles with hollow walls

Definitions

• the invention relates primarily to an extruded, radially stretched plastic pipe.
• British Patent Specification 1,382,580 discloses a radially stretched plastic pipe in which the plastic is a foam plastic.
• the foam plastic pipe is placed in a cylindrical mould, after which the pipe, while it is being heated above its glass transition temperature, is subjected to the pressure from a fluid acting inside the pipe, as a result of which the pipe is stretched out until it comes into contact with the inside walls of the mould.
• the temperature at which the stretching takes place is a temperature which is below the melting point of the foam plastic.
• the stretching procedure can be applied to foam plastic of various types; in particular, the process described in said patent specification is applied to the stretching of a pipe made of PVC foam plastic.
• the possibility of stretching plastic pipes is not limited to the stretching of foam plastic pipes and that, in particular, an extruded, radially stretched plastic pipe, which is characterized in that the plastic of which the pipe is made is solid and the wall of the pipe contains cavities and/or recesses and/or protuberances which are provided during the primary shaping, has very good properties as regards impact strength, modulus of elasticity, creep and resistance to stress corrosion.
• the pipes as described above have a smooth inside wall.
• the possibilities in this respect are governed by the nature of the plastic concerned, the wall thickness of the pipe and the required properties to be achieved; in general, however, the pipe will have an outside diameter which is at least 25% greater than the outside diameter of the same pipe in the unstretched state.
• the stretching of the pipe types described above is not limited to a stretching in the radial direction; the extruded pipe according to the invention is also advantageously stretched in the longitudinal direction.
• the pipe according to the invention is advan ⁇ tageously manufactured from a polyalkene such as polypro- pene or polyethene or essentially from polyvinyl chloride.
• European Patent Specification 0,072,064 also describes a procedure and apparatus for discontinuously biaxially stretching a solid-wall pipe, the pipe equally not being provided with cavities and/or recesses and/or protuberances, as is the case in the pipe according to the invention.
• European Patent Application 0,163,336 describes, in particular, an apparatus for biaxially stretching solid-wall pipes with smooth inside and outside wall.
• the invention also relates to a process of manufacturing a radially stretched plastic pipe at least comprising the steps of: a) bringing the pipe to a temperature which is above the glass transition temperature of the plastic concerned but below the melting point thereof, b) radially stretching the pipe, c) cooling the pipe.
• the starting point is a pipe made of solid plastic, the wall of the pipe containing cavi ⁇ ties and/or recesses and/or protuberances which are provided during the primary shaping and in that the pipe is sized after being extrusion-moulded and is stretched below the extrusion temperature.
• the starting point for manufacturing a radially stretched foam pipe is a finished pipe which at ambient temperature and which is then heated to above the glass transition temperature and is stretched at said temperature; such a treatment may also be applied to the pipes which are considered in the present invention.
• Said tempering may be carried out in a plurality of ways, of which the most important consist in keeping the pipe for a suitable period of time at a temperature which is equal to the stretching temperature or heating the pipe to a suitable, usually relatively low, value above the stretching temperature, keeping it at said temperature for a suitable time, after which it is cooled again ⁇ to the stretching temperature.
• said temperature is at least 50°C below the temperature at which the pipe is moulded.
• extrusion is carried out, for example, at 196°C, after which the pipe is sized and is cooled to 120°C before the stretching operation is carried out.
• a stretch ⁇ ing percentage of at least 25% will in general be adhered to in the process according to the invention both in the radial direction and in the axial direction; the precise value of stretching is, however, dependent on the dimensions of the pipe started from and the type of plastic from which the pipe is manufactured.
• the procedure according to the present invention may be carried out both discontinuously and continuously; in both cases, similar results are obtained.
• both stretching operations may be carried out either simultaneously or with separation in time using apparatuses suitable for the purpose. If the operations are carried out with separation in time, the axial stretching may optionally be carried out prior to, or subsequent to, the radial stretching.
• Figure 1 shows diagrammatically the original state of a pipe in which longitudinal channels are provided
• Figure 2 shows a pipe with external solid ribs.
• Figure 1 shows a pipe 1 containing axial channels and a wall 2 and channels 3 extending in the longitudinal direction.
• the plastic of the wall 2 is a solid plastic; the presence of the channels 3 provides the circumstance that the weight per unit length of the pipe containing chan ⁇ nels is at least 20% lower than the weight of a corresponding pipe without channels.
• Solid plastic is understood to mean in this case a material which is not a foam plastic material; i.e. a material that, apart from any naturally present pores, contains no cavities except macroscopic cavities in the form of channels 3 formed by the manufacturing.
• Figure 2 shows a pipe 20 provided with external solid ribs and having a continuous wall 21 and ribs 22.
• the weight of a unit length of such a ribbed pipe is at least 20% lower than the weight of a corresponding solid pipe having an outside diameter Du and an inside diameter Di.
• solid is understood to mean a plastic which is not a foam plastic.
• the improved impact strength of the pipes according to the invention is of great impor ⁇ tance because, in that case, a lower weight is accom- panied by a higher impact strength, which is very attrac ⁇ tive for many applications.
• con ⁇ veyance of domestic and industrial waste water con ⁇ veyance of rain-water and the like in sewage systems.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Shaping Of Tube Ends By Bending Or Straightening (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Ultra Sonic Daignosis Equipment (AREA)
• Prostheses (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19852921

Family Applications (2)

Family Applications Before (1)

Country Status (9)

Families Citing this family (2)

Family Cites Families (5)

• 1988
  • 1988-09-16 NL NL8802305A patent/NL8802305A/nl not_active Application Discontinuation
• 1989
  • 1989-09-12 FI FI911294A patent/FI911294A0/fi not_active Application Discontinuation
  • 1989-09-12 EP EP89202304A patent/EP0362919B1/de not_active Expired - Lifetime
  • 1989-09-12 AU AU43067/89A patent/AU4306789A/en not_active Abandoned
  • 1989-09-12 WO PCT/NL1989/000067 patent/WO1990002648A1/en not_active Ceased
  • 1989-09-12 DE DE68917243T patent/DE68917243D1/de not_active Expired - Lifetime
  • 1989-09-12 AT AT89202304T patent/ATE109398T1/de active
  • 1989-09-12 EP EP89910676A patent/EP0434740A1/de active Pending
  • 1989-09-12 ES ES89202304T patent/ES2060743T3/es not_active Expired - Lifetime
• 1991
  • 1991-02-27 DK DK034591A patent/DK34591A/da unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events