Method and apparatus for continuously extruding single-wall ribbed conduits of plastics or other mouldable material

Claim 2

Single-wall pipe, tube or like conduit having smooth inner surfaces and a mechanical-strength enhancing pattern of walls, flanges or ridges on the outer surface thereof, the conduit being made of plastics or like extrudable material, characterized in, that the conduit (9,44) is of a composite structure and comprises at least two different concentric parts (44", 44"'), these parts being made of different materials.

Claim 3

Conduit according to claim 1, characterized i n, that the conduit (9,44) comprises an outer part (44") which is made of a certain material and comprises said pattern of flanges or ridges, the conduit further comprises an inner part made of another material.weldable with good adhesion to the first.

Claim 4

Conduit according to claim 2, characterized i n, that, the conduit being meant for heat exchangers, the outer part is made of a highly modified plastics material,comprising mineral or metal particles, the material having good mecharical strength and good thermal conductivity, and in that the inner part is made of a substantially unmodified plastics material having good resistance to e.g. chemically aggressive substances.

Claim 5

Conduit according to claim 1, 2 or 3, characterized in, that it is manufactured by means of a method in which material is fed from two ormore extruders to an extruder nozzle and further into a moulding apparatus comprising mould-jaw chains (1,2) which move adjacent one another along a moulding line and include mould-jaw parts (3) whose mutually opposing surfaces (48) in said moulding line have a form which corresponds to the desired form of the outer surface of the conduit (9,44) under manufacture, and in which method said material is pressed against said surfaces of said mould-jaw parts along at least a part of the moulding line, and in which said mould-jaw chains are caused to move away from one another subsequent to passing said moulding line, said mould-jaw parts therewith releasing their engagement with the outer surface of the moulded conduit, and in which the conduit under manufacture is produced in a known manner in at least two stages, by supplying said material to said moulding line at at least two separate locations, a first location and a second location, located the second after the first in the direction of conduit movement; and in which the material (10) at said first location is delivered from a first channel (18) of circular, tubular cross-section and is pressed against the mould-jaw parts (3) by means of air or some other medium under pressure and/or is drawn by suction against said mould-jaw parts by means of a vacuum pressure exerted through passages (34) in said mould-jaw parts, whilst adjusting the quantity of material supplied and the pressure and/or vacuum pressure at said first location so that grooves or recesses in the mould-jaw parts (3), corresponding to outwardly protruding parts (63) of the conduit, are filled at least to the bottom thereof; and in which additional material (30) for producing a single-wall conduit is supplied to said second location from a further channel (20) of circular, tubular cross-section formed between a first, external mandril (17) and a second, internal mandril (19), and discharging into a cavity (30) located between the input end (40) of a smoothing mandril (31) and the ends (25,26) of the mandrils (17,19) facing the smoothing mandril (31), and is pressed against the material supplied at said first location by means of air or some other medium under pressure, said pressurized medium being supplied to said cavity (30).

Claim 8

A method according to claim 5, characterized in, that the material for the respective channels (18,20) is fed from at least two extruders, different materials being fed to the respective channels (18,20), whereby a conduit (9,44) of a compositestruc- ture is produced which comprises at least two different concentric parts (44", 44'"), these parts being made of different materials.

Claim 10

A method according to claim 7, characterized in, that said spacing elements (33) form lead-throughs (33) for passages (32) which extend transversely through said second channel (20) and through which pressurized medium is supplied to said first location, said passages (32) extending from a pressurized-medium supply channel (23) extending axially within the inner mandril (19).

Claim 14

A method according to claim 11, characterized in, that there is provided two mould-jaw chains (1,2), in which each mould-jaw part (3) includes two mould-jaw sections (3', 3").

Claim 15

A method according to claim 11 or claim 12, characterized in, that each longitudinal row of mould-jaw sections (3', 3") of the mould-jaw chains is driven by means of a chain (51', 51") or the like arranged adjacent said sections (3', 3").

Claim 16

A method according to claim 13, characterized in, that the drive chains (51', 51") for each section (3', 3") of said mould-jaw parts (3) extends around a common rotation axis, at least in the vicinity of the zone (56, 57) where the jaw sections (3', 3") are moved away from one another.

Claim 18

A method according to claim 15, characterized by a conduit (9,44) having on the outer surface thereof intermediate walls (63) forming a diamond-shaped network, said network being formed in the moulding line by means of continuous grooves formed in the mould-jaw parts (3) and extending in left-hand and right-hand helices, or in the longitudinal direction and peripheral direction in the forming line.

Claim 20

Apparatus for producing a single-wall conduit having smooth inner surface from plastics material or a corresponding extrudable material, said apparatus comprising at least one extruder, chains of mould-jaws for forming a moulding line, and an extrusion nozzle for supplying molten or plasticized material to said form line, said apparatus further including pressure means for pressing the material against mutually facing surfaces of the mould-jaw partsincorporated in said mould-jaw chains in at least a part of said moulding line, and further comprising means for cooling the moulded conduit, and means by means of which the mould-jaw chains are caused to move apart subsequent to passing said moulding line, said mould-jaw parts being arranged to release their engagement with the outer surface of the moulded conduit, characterized in that said conduit (9,44) is arranged to be produced in a known manner in at least two stages by supplying material to the moulding line at at least two mutually separate locations, a first location and a second location, located the second after the first in the direction of movement of said material; in that means are provided for adjusting the amount of material supplied and the pressure and/or vacuum pressure applied at said first location in a manner such that grooves or recesses provided on the mould-jaw parts (3) and corresponding to outwardly projecting parts (63) of the conduit are filled with said material at least to their bottom portions; in that for the purpose of pressing supplied material against the mould-jaw parts (3) means are provided for supplying pressurized air or some other pressurized gas to at least said second location and where, preferably for drawing supplied material (10) by suction against the mould-jaw parts (3) a vacuum pressure is intended to be applied through passages (34) in the mould-jaw parts at least in the vicinity of said first location, and where a first channel (18) of circular, tubular cross-section is provided for supplying material (10) to said first location, said first channel opening into an annular space (29) formed between a first, outer mandril and the mould-jaws and arranged to be supplied with said pressurized medium; and in that further material for producing a single-wall conduit is intended to be supplied to said second location, where a further channel (20) of circular, tubular cross-section is provided for supplying material (10) to said second location, said channel being formed between the first, outer mandril (17) and a second, inner mandril (19) and opening into a space (30) which is defined, when seen in the direction of movement of the material, by the ends (25,26) of the mandrils (17,19) facing the smoothing mandril (31) and said smoothing mandril (31), and in that means are provided for supplying said pressurized medium to said space (30).

Claim 21

Apparatus for producing a single-wall conduit having smooth inner surface from plastics material or a corresponding extrudable material, said apparatus comprising at least one extruder, chains of mould-jaws for forming a moulding line, and an extrusion nozzle for supplying molten or plasticized material to said form line, said apparatus further including pressure means for pressing the material against mutually facing surfaces of the mould-jaw partsincorporated in said mould-jaw chains in at least a part of said moulding line, and further comprising means for cooling the moulded conduit, and means by means of which the mould-jaw chains are caused to move apart subsequent to passing said moulding line, said mould-jaw parts being arranged to release their engagement with the outer surface of the moulded conduit, characterized in that said conduit (9,44) is arranged to be produced in a known manner in at least two stages by supplying material to the moulding line at at least two mutually separate locations, a first location and a second location, located the second after the first in the direction of movement of said material; in that means are provided for adjusting the amount of material supplied and the pressure and/or vacuum pressure applied at said first location in a manner such that grooves or recesses provided on the mould-jaw parts (3) and corresponding to outwardly projecting parts (63) of the conduit are filled with said material at least to their bottom portions; in that for the purpose of pressing supplied material against the mould-jaw parts (3) means are provided for supplying pressurized air or some other pressurized gas to at least said second location and where, preferably for drawing supplied material (10) by suction against the mould-jaw parts (3) a vacuum pressure is intended to be applied through passages (34) in the mould-jaw parts at least in the vicinity of said first location, and where a first channel (18) of circular, tubular cross-section is provided for supplying material (10) to said first location, said first channel opening into an annular space (29) formed between a first, outer mandril and the mould-jaws and arranged to be supplied with said pressurized medium; and in that further material for producing a single-wall conduit is intended to be supplied to said second location, where a further channel (20) of circular, tubular cross-section is provided for supplying material (10) to said second location, said channel being formed between the first, outer mandril (17) and a second, inner mandril (19) and opening into a space (30) which is defined, when seen in the direction of movement of the material, by the ends (25,26) of the mandrils (17,19) facing the smoothing mandril (31) and said smoothing mandril (31), and in that means are provided for supplying said pressurized medium to said space (30).

Claim 22

Apparatus according to claim 18, characterized i n that the smoothing mandril (31) has a softly rounded, convex shape at its input end (37).

Claim 23

Apparatus according to claim 18 or 19, characterized in that spacing elements (33,33') are arranged in said second channel (20) in the region of the ends (25,26) of the mandril (17,19) facing the smoothing mandril (31), for guiding said second, inner mandril (19) in relation to said first, outer mandril (17).

Claim 24

Apparatus according to claim 20, characterized i n that said spacing elements (33) form lead-throughs (33) extending through the walls of said second channel (20) for accomodating passages (32) for supplying pressurized medium to said first location, said passages (32) extending transversally from a pressurized-medium supply channel (23) extending axially within the inner mandril (19).

Claim 25

Apparatus according to claim 18, 19, 20 or 21 characterized in that spacing elements (33') are also provided in said first channel (18) for guiding said first mandril (17) in relation to an outer sleeve (14), said outer sleeve (14) forming together with said first mandril (17) said first channel (18).

Claim 26

Apparatus according to claim 18, 19, 20, 21 or 22, characterized in that the smoothing mandril (31) includes means (45) for heating said mandril to a temperature such that the material on the inner surface (43) of the conduit (44) formed in said moulding line is held in a molten or plasticized state to an extent such that the inner surface can be substantially smoothed by sliding action with the smoothing mandril (31).

Claim 27

Apparatus according to claim 20, 21, 22 or 23 characterized in that the spacing elements (33,33') are arranged to offer but low resistance to the material (10) passing said elements (33), said elements preferably being streamlined in the flow direction of the material (10) and having sharp end portions such that the material is divided and sealed off subsequent to passing said elements (33), under low resistance.

Claim 28

Apparatus according to claim 18, 19, 20, 21, 22, 23 or 24, characterized in that said moulding line is formed by means of at least two mutually parallel mould-jaw chains (1,2); in that the mould-jaw parts (3) of said mould-jaw chains are preferably symmetrically divided in the longitudinal direction of the moulding line; and in that each mould-jaw part (3) includes preferably two mould-jaw sections (3',3") which are arranged for movement towards and away from one another and to move adjacent one another to form a mould-jaw part (3) in said moulding line.

Claim 29

Appparatus according to claim 25, characterized i n that means (59,60,61), such as guide rails or the like co-acting with the mould-jaw chains, are provided by means of which each mould-jaw section (3',3'') of the mould-jaw parts (3) is arranged to move in a direction away from another mould-jaw section subsequent to passing said moulding line, substantially at the same time as the mould-jaw parts (3) are moved apart, so that each mould-jaw section (3',3") is moved substantially radially outwards in relation to the conduit part formed in the moulding line by means of said mould-jaw secion (3',3")-

Claim 30

Apparatus according to claim 25.or claim 26, characterized in that two mould-jaw chaing (1,2) are provided, in which each mould-jaw part (3) includes two mould-jaw sections (3',3").

Claim 31

Apparatus according to claim 25,26 or 27, characterized in that provided at each longitudinal row of mould-jaw sections (3',3") of said mould-jaw chains is a drive chain (51',51") or the like for driving said chain of mould-jaws.

Claim 32

Apparatus according to claim 28, characterized i n that the drive chains (57',51") for the sections (3',3") of each mould-jaw part (3) extend around a common rotation axis at least in the vicinity of the zone (56,57) where said sections are arranged to be moved away from one another; and in that said sections are arranged to be moved apart by means of wedge-shaped means acting against the drive chains, or by means of guide rails co-acting with said sections (3',3").

Claim 33

Apparatus according to claim 25,26,27,28 or 29, characterized in that the sections (3',3") of each mould-jaw part (3) are guided relative to one another when moved towards or away from each other by means, for example, of at least one guide pin (54) arranged adjacent the one jaw section (3') and having a narrowing and square or elongated rectangular cross-section and a corresponding recess or corresponding recesses (55) in the other jaw section (3")

Claim 34

Apparatus according to claim 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30, characterized in that the inner surface of the mould-jaw parts (3) is designed such as to impart to the outer surface of the conduit (9,44) a pattern (62,63) comprising recesses (62) which extend substantially radially inwards from the outer cylindrical surface (44') of the conduit and which form therebetween a system of preferably thin intermediate walls (63), where the depth of said recesses (62) corresponds to a substantial part of the total wall thickness of the conduit (44).

Claim 35

Apparatus according to claim 31, characterized i n that the mould-jaw parts (3) include continuous grooves for forming said intermediate walls (63), said grooves being arranged to form a left-hand and right-hand helices in the moulding line or longitudinal grooves and grooves which extend circumferentially in the moulding line, thereby to provide a diamond-shaped network of intermediate walls (63).

Claim 36

Apparatus according to claim 31, characterized i n that the mould-jaw parts (3) include outwardly projecting pegs for forming said recesses (62), said pegs having a cross-sectional shape of preferably circular configuration or a configuration which corresponds substantially to a regular hexagon.