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
  • B29D99/00—Subject matter not provided for in other groups of this subclass
  • B29D99/0025—Producing blades or the like, e.g. blades for turbines, propellers, or wings
• • 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
  • B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
  • B29C37/005—Compensating volume or shape change during moulding, in general
• • 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
  • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
  • B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles
  • B29C39/021—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles by casting in several steps
  • B29C39/025—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles by casting in several steps for making multilayered articles
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
  • F01C1/00—Rotary-piston machines or engines
  • F01C1/08—Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing
  • F01C1/082—Details specially related to intermeshing engagement type machines or engines
  • F01C1/084—Toothed wheels
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2230/00—Manufacture
  • F04C2230/20—Manufacture essentially without removing material
  • F04C2230/22—Manufacture essentially without removing material by sintering
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
  • F05C2225/00—Synthetic polymers, e.g. plastics; Rubber
  • F05C2225/04—PTFE [PolyTetraFluorEthylene]

Definitions

• the present invention relates to a method for manufacturing helical screw rotors in accordance with the preamble of claim 1.
• the invention also relates to rotors manufactured in accordance with the method. Normally, helical screw rotors are machined from solid metal blanks. Moreover, the rotors have a complicated geometric shape, which places great demand on accuracy in manufacture. Machining of the rotors from solid rotor blanks also involves the removal of large quantities of material from the blank. All of which results in long manufacturing times and high production costs.
• Swedish Patent Applicatin No. 8603720-7 and PCT/SE87/00397 teach a number of known methods for the manufacture of helical screw rotors, in which manufacture is simplified by moulding a plastic surface layer onto a plastic or a metal rotor body, which in turn is mounted on a metal shaft. These konwn methods are based on the concept of first producing a rotor body with no particular attention to measurement accuracies, and then moulding onto the body a surface layer formed to exact measurements. The desired result is normally achieved, when the rotor body is made of metal.
• plastic-moulded rotor bodies represent a considerable simplification in the manufacture of such bodies, subsequent shrinkage of the plastics material creates drawbacks which are not found when casting or moulding other kinds of plastic objects, where sub- sequent shrinkage of the plastics material can be anticipated and compensated for.
• the particular difficulties which manifest when moulding helical screw rotors relate to the helically extending cams, which as a result of the shrinkage become disterted in a manner which cannot readily be calculated prior to manufacture. This distortion changes the pitch of the cams in the vicinity of the ends thereof.
• the rotor body is moulded, injection moulded, etc., from several layers of solidifying material, suitably a material composite, such as to allow especially shrinkage-induced distortion of the lands or threads to be eliminated, by application of the outer layer.
• a material composite such as to allow especially shrinkage-induced distortion of the lands or threads to be eliminated.
• the degree of distortion and measurement deviations which remain despite moulding the rotor body in several layers will not be so great as to prevent the distortion and measurement deviations from being eliminated, by moulding the outer layer of polymer-based material onto the rotor body, which layer can then be made relatively thin and consequently will have negligible shrinkage.
• the rotor body can be moulded in accordance with one of a number of different methods, including sintering, using many different kinds of material, as defined in claims 2 to 7. All of the layers of the rotor body will preferably be made from a polymer-based material, suitably a material composite, i.e. a material reinforced with fibres in accordance with known techniques.
• a material composite i.e. a material reinforced with fibres in accordance with known techniques.
• the illustrated rotor which is a male rotor, includes a shaft 1 , which may be made of steel or a reinforced plastics material of extremely high bending strength, and a rotor body 2 which has moulded thereon an outer layer 3 of polymer-based material.
• the illustrated rotor body 2 comprises two body layers 21, 22 of polymer-based material, of which the innermost body layer 21 is somewhat thicker than the outermost layer 22. Shrinkage of the body layer 21 shall have terminated, before moulding of the outer layer 22 is complete. Similarly, shrinkage of the outermost of said two body layers shall have terminated, prior to moulding of the thin outer layer 3 being completed, therewith to achieve the highest possible measurement accuracy and the least possible distortion of the rotor lands, in the simplest possible manner.
• each layer will preferably be as uniform as possible.
• the shaft embodiment with helical lands or threads described in the aforesaid PCT/SE86/00109 can be used to this end, and when different materials are used, the thermal coefficient of expansion of the layers should be so selected in respect of the material of adjacent layers and the material of the shaft and the outer layer 3 as to ensure that the smallest possible differences in thermal expansion are obtained.
• the layer 21 is made of polyetherimide with a 30 % glass-reinforcement.
• ULTEM 2300® General Electric
• the outer layer 3 consists solely of polytetraflouroethene plastic (Teflon®) and varies in thickness from about 1/100 mm to 1-2 mm depending on the extent of subsequent shrinkage of the rotor body, prior to moulding of the outer layer 3 being completed.
• Teflon® polytetraflouroethene plastic
• the various layers may include particles of metal and or ceramic material, in addition to reinforcement fibres of greater or smaller lengths.
• At least one. of the outer layers of the rotor body may comprise a porous plastic material, in which case the density will preferably increase in a direction towards the two faces of the layer.

Landscapes

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=20371929

Family Applications (1)

Country Status (5)

Cited By (3)

Families Citing this family (2)

Citations (3)

• 1988
  • 1988-04-07 SE SE8801276A patent/SE463040B/sv not_active IP Right Cessation
• 1989
  • 1989-04-04 WO PCT/SE1989/000173 patent/WO1989009881A1/en active IP Right Grant
  • 1989-04-04 EP EP89904637A patent/EP0411000B1/en not_active Expired - Lifetime
  • 1989-04-04 JP JP1504229A patent/JP2833808B2/ja not_active Expired - Fee Related
  • 1989-04-04 DE DE89904637T patent/DE68907054T2/de not_active Expired - Fee Related

Patent Citations (3)

Non-Patent Citations (1)

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