METHOD OF MANUFACTURING EXTRUDED PIPES AND APPARATUS FOR CARRYING OUT THE METHOD

Abstract: A method of manufacturing extruded pipes where plasticized material, for example plastic material, is advanced to an extrusion nozzle comprising a circular gap (2). The method is especially characterized in that the material is transported axially in said gap (2) while material is moved, for example rotated, in the circumferential direction of the gap (2) so that the material at least partially is caused to assume an orientation deviating from the axial direction, whereby a non-axial orientation will prevail in theextruded pipe (3) and increase the strength. The invention also relates to an apparatus for carrying out the method.

Description: Method of manufacturing extruded pipes and apparatus for carrying out the method This invention relates to a method of manufacturing ex¬ truded pipes where plasticized material, for example plastic material, is advanced to an extrusion nozzle comprising a circular gap. The invention also relates to an apparatus for carrying out the method. At known methods the material is transported through an extrusion nozzle substantially only in parallel with the longitudinal direction of the extruded pipe, where¬ by the molecules of the material are oriented in said longitudinal direction. The orientation thus obtained brings about a certain reinforclement effect in said longitudinal direction, but not, for example, in the circumferential direction of the pipe. The present invention relates to a method and an app¬ aratus, at which orientation occurs in several direct¬ ions and thereby bring about reinforcement in several directions. It is hereby possible to reduce the necess- ary wall thickness for definite strength properties and thereby to reduce the amount of plastic or the like. The invention, thus, relates to a method of manufactur¬ ing extruded pipes, where plasticized material, for example plastic material, is advanced to an extrusion nozzle comprising a circular gap. The method is especially characterized in that the mat¬ erial is transported-axially in said gap while material is caused to move, such as to rotate, in the circumfer¬ ential direction of the gap, so that the material at least partially is caused to assume an orientation dev¬ iating from the axial direction, whereby non-axial or¬ ientation will prevail in the extruded . pipe and in¬ crease the strength. The invention also relates to an apparatus for manufact¬ uring extruded pipes, ' comprising devices for advancing plasticized material, for example plastic material, to an extrusion nozzle comprised in the apparatus, which nozzle comprises a circular gap, through which material is intended to pass in axial direction. The apparatus is especially characterized in that it comprises devices for moving, for example rotating, material substantially in the circumferential direction 0 of the gap, so that the material at least partially is caused to assume an orientation deviating from the axial direction, whereby non-axial orientation will prevail in the extruded pipe and increase the strength. The invention is described in greater detail in the 5 following, with reference to embodiments thereof and to the accompanying drawings, in which Fig. 1 is a schematically shown central section in parallel with the longitudinal direction of the extrusion nozzle at a first embodiment of an apparatus according to the 0 invention, Pig. 2 shows a slitted tubular body intend¬ ed to be placed rotatably in the circular gap of the extrusion nozzle, Pig. 3 is a view from the right in Pig. 2 of the body according to Pig..2, Fig. shows schematically an extruded pipe according to the invent- 5ion adjacent the outer end of the nozzle according to Pig. 1, Pig. 5 shows schematically a portion of a sec¬ ond embodiment of the extrusion nozzle at an apparatus • according to the invention, seen from the outer end of the nozzle, Fig. 6 is a vertical central section 0through a portion of the nozzle according to Pig. 5, Fig. 7 shows schematically a portion of a third embodi¬ ment of the nozzle at an apparatus according to the invention, seen as in Pig. 5 . Fig. 8 is a vertical central section through a portion of the nozzle acc- 5ording to Fig. 7_ and Pig. 9 is a perspective view OMPΓ of a portion of a pipe manufactured by the apparatus ace- . o-ding to Pigs. 5 and 6. In Pig. 1 the numeral 1 designates a feed passageway for the supply of plasticized material, for example so-call- ed HD-polyethene or PVC, to the extrusion nozzle. Also other material, such as rubber, can be extruded. The nozzle comprises a circular gap 2, through which mater¬ ial is intended to pass in axial direction, and where a pipe 3, Pig. 4, formed of the material is intended to run out through the gap 2 at the outer end 4 of the nozzle. At said outer nozzle end 4 a forming space 2' is located, which at the embodiment according to Pig. 1 constitutes a portion of the gap 2. The gap 2 is defined by an outer defining wall 5, which preferably consists of the shell surface 5 of a bore in a block β or the like, and an inner defining wall 7, which preferably consists of the shell surface 7 of an axle 8 or the like, which is located concentrically in said bore and enters the bore where the bore joins the feed passage- way 1, i.e. at the infeed space 1 * for material to the gap 2. According to a first embodiment of an apparatus accord¬ ing to the invention, a tubular body 9, a pipe 9, is located rotatably and concentrically in the gap 2. Said tubular body 9 is intended to move, rotate the material in the circumferential direction of the gap 2 over the entire cross-section of the gap 2 and, ' thus, also ad- j.acent the inner defining wall 7 and the outer defining wall 5 of the gap 2. According to this embodiment, the pipe 9 is guided in the gap 2 by means of the axle 8 and bore. At its free end 10 projecting out of the block β, the pipe 9 is provided with a gearwheel 11 or the like intended to co-operate with an additional gear¬ wheel 12 or the like connected to a drive equipment (not shown). According to the invention, the pipe 9 OMPI m?o comprises at least one longitudinal slit 13, Figs. 1-4, extending from the infeed space 1' to the forming space 2' at the outer end 4 of the nozzle where the ' end 13" of the slit 13 joining the space 2' , thus, constitutes a rotatable outlet 13" for ■ material. At the second embodiment shown iri Pigs. 5 and β of an apparatus according to the invention, two pipes 14,15, tubular bodies 14,15, one dinner one 14 and one outer one 15, join said inner defining wall 7 and, respectively, outer defining wall 5 and are rotatable preferably in opposed directions as indicated by the arrows in Pig. 5 and form between themselves a space 16 for substantially axial transport of material. Each pipe 14,15 comprises at least one longitudinal slit 17 . 18, which preferably extend from the infeed space 1' all the way to the form¬ ing space 2' , where outlets 17", 18", thus, are locat¬ ed. In Fig. 6 an embodiment is shown by fully drawn lin¬ es, where the space Iβ and slit 17 are intended to be fed with material from the space 1' via the slit 18. It is, of course, imaginable that the slit .14, and thereby also the space 16, also are fed with material via rec¬ esses 19 in the outer pipe 15, where the recesses 19 are in contact with the space 1' and slit 17, as shown by dashed line in Pig. 6. At the third embodiment shown in Pigs. 7 and 8 of an apparatus according to the invention, two pipes 20,21 are provided, an inner one 20 and an outer one 21, which join said inner defining wall 7 and, respectively, outer ' defining, wall 5, and preferably are rotatable in opposed directions. At this embodiment, however, the pipes 20,21 join each other so that there is substant¬ ially no space lβ between the pipes. Also at this embod¬ iment, each pipe 20,21 comprises at least one slit 22 and, respectively, 23, which extend in a way correspond- ing substantially to the slits 17,18 and comprise out¬ lets 22", 23". At this embodiment, the slit 22 in the ^ j E OMPI inner pipe 20 preferably is supplied with material from the space 1, 1' via recesses 24 in the outer pipe 21, as shown schematically in Pig. 8. At the pipe portion shown in Pig.9., the layers or port- ions extending in circumferential direction, which are formed at the manufacture according to Pigs. 5 and β, are shown schematically. The outer layer 18' is .brought about by means of the slit 18 of the pipe 15 and extends helically with clockwise pitch. The intermediate layer ι6' is brought about by means of the space 16 between the pipes 14,15 and extends substantially with axial orientation. The inner layer 17' is .brought about by means of the slit 17 of the pipe 14 and extends helic¬ ally with counter-clockwise pitch. At the manufacture according to Pi s. 7 and 8 there will be no layer 16' , because of the absence of a space lβ between the pipes. The thickness of the space lβ, of course, can be var¬ ied as desired, from thick to very thin or non-exist¬ ent. At the embodiments described above, continuously rotat¬ ing ' tubular bodies, pipes, were assumed to be comprised. It is, however, possible to use an oscillating rotation movement, which reciprocates in the circumferential direction of the gap 2. In this case the material will be laid out in an obvious manner in subsequent helical sections with alternating pitch direction. It is also possible to imagine embodiments where the defining walls 5,7 of the gap 2 are rotatable, prefer¬ ably in opposed directions, whereby the material is moved in the circumferential direction of the gap 2 at least adjacent said defining walls during the axial material transport. The defining walls can be rotated in the substantial, gap ' 2 and/or the ' forming- space 2' defining:.the walls. It is also imaginable that only one wall is rotated.- Embodiments can also be imagined which lack the subst¬ antial gap 2, and material is transported ih at least one closed passageway in a rotatable body all the way to outlets at the forming space 2' located in circumfer- ential direction of the forming space 2'. The gap 2, thus, consists only of the forming space 2' . The method according to the invention and the mode of operation of the apparatus according to the invention substantially should have become apparent from the afore- said. By moving, for example rota-ting, material in the circum¬ ferential direction of the gap 2, 2' , orientation is obtained which deviates from the axial direction, where¬ by non-axial orientation will prevail in the extruded pipe. At the embodiment shown in Pigs. 1-4, thus, material is fed in from the passageway 1 in the space 1" to the slit 13 in the pipe 9. -whereby the material is transported in the longitudinal direction of the slit 13 3 i.e. axi- ally in the gap 2, at the same time as the material in the slit is rotated in circumferential direction of the gap 2. Hereby, from the slit end located adjacent the outer end 4 of the nozzle a strand 3' of material is laid out substantially in helical configuration, Pig. 4. Each new strand turn fuses with the one laid out last. The molecules in the central portion 13' of the strand, pipe wall, Pig. 4, calculated in radial direction of the pipe 3_ will be oriented hereby in a preferred dir¬ ection, viz. substantially the direction, in which said helix extends, i.e. in the longitudinal direction of the strand . In the inner and outer portions 7' and 5' of the strand, pipe wall, calculated in radial direction of the pipe, i.e. the portions, which were located closest to and in contact with the defining walls 5,7 of the gap 2, the molecules, due to the rotation and friction against said defining walls, will be oriented in a pre¬ ferred direction, which differs from the preferred dir¬ ection in the central portion 13', and which direction depends a.o. on the advancing speed in the slit 13 and the rotation speed of the pipe 9. By the differences in orientation thus obtained between the molecules in the central portion 13' of the pipe wall 'and the inner and outer surface of the pipe wall, a reinforcement of the pipe 3 is obtained at the same time as there is a deviation from axial orientation. At the embodiment sho.wn in Figs. 5 and 6, two strands are laid out, Pig.9 , one outer strand 18' and one inner strand 17' . in preferably opposedly directed helical configurations, forming an outer portion 18' and an inn- er portion 17', while the intermediate portion lβ' is discharged substantially axially, ..hereby differences in preferred orientazion of the molecules arise in the intermediate layer lβ', on one hand, and in the outer layer 18' and inner layer 17' , on the other hand. Pur- ther differences in orientation arise adjacent the outer portion of the portion 18 * and inner portion of the portion 17' , due to the rotation and friction against the defining walls of the gap 2, as described above. At the embodiment according to Pigs. 5 and β, more extens- ive differences in orientation are obtained " than at the embodiment according to Pigs. 1-4. The mode of operation at the embodiment according to Pigs. 7 and 8, where the intermediate layer is substant¬ ially lacking, should be apparent from the description above. As should have become clear from the aforesaid, the in¬ vention renders it possible to manufacture reinforced pipes in a very simple and inexpensive way, where rein¬ forcement is obtained by differences in preferred orient- _ r - - o . U1 o vn

Claims: Claims 1. A method of manufacturing extruded pipes where plast¬ icized material, for example plastic material, is advanc¬ ed to an extrusion nozzle comprising a circular gap, c h a r a c t e r i z e d i n that the material is transported axially in said gap (2) while material is caused to be moved, for example rotated, in circumferent¬ ial direction of the gap (2) so that the material at least partially is caused to assume an orientation devi- ating from the axial direction, whereby non-axial orien¬ tation will prevail in the extruded pipe (3) and incre¬ ase the strength. 2. A method as defined in claim 1, c h a r a c t e r ¬ i z e d i n that the material is supplied to a forming space (2') at the outer end (4) of the extrusion nozzle by means of at least one outlet for material which rotates continuously or oscillating in circumfer¬ ential direction of the gap (2). 3. A method as defined in claim 1 or 2, c h a r a c t- e r i z e d i n that the material is caused to move in the circumferential direction of the gap (2) at least adjacent the inner (7) and outer (5) defining wall of the gap (2) by means of at least one rotary tubular body (9,14,15 . 20,21) whereby the material (5'_7',17 . 18') adjacent said defining walls (5,7) will be oriented in another direction than certain intermediate portions (13',lβ'), and that- the material is fed-in in at least one longitud±narl slit (13,17,18,22,23) in the body (9, 14,15,20,21), from which slit material is discharged to a forming space (2') located at the outer end (4) of the extrusion nozzle. 4. A method as defined in claim 3, c h a r a c t e r ¬ i z e d i n that the material is transported subst¬ antially axially in a space (lβ) formed between two pipes, an inner one (14) and an outer one (15), and that the pipes (14,15) joining said inner (7) and, respectively, said outer (5) defining wall are caused to rotate in preferably opposed directions, whereby material is fed- -in in at least one longitudinal slit (17,18) in each pipe (14,15), from which material is discharged to the forming space (2'). 5. A method as defined in claim 4, c h a r a c t e r¬ i z e d i n that said space formed between the pipes (20,21) is very small or non-existing, and the.plastic material is transported axially substantially only in said slits (22,23). 6. A method as defined in claim 4 or 5, c h a r a c t¬ e r i z e d i n that material is supplied to the slit(s) (17,22) of said inner pipe (14,20) at recesses (19,24) in the outer pipe (15,21). 7. A method as defined in claim 3,4,5 or β, c h a r- a c t e r i z e d i n that distribution and size of said orientation deviations from the axial direction part¬ ially are controlled by adjusting and controlling the advancing speed of the material in said slit(s) (13,17, 18,22,23) in relation to the rotation speed of the pipe(s) (9,14,15,20,21). 8. A method as defined in claim 2,3,4,5,6 or 7, c h a r a c t e r i z e d i n that the length of the portion (25) of said gap (2) adjacent the outer end (4) of the extrusion nozzle, i.e. the length of the forming space (2'), is adjusted so that greatest poss¬ ible orientation deviations are obtained. 9. A method as defined in claim 1, c h a r a c t e r - i z e d i n that deviations in orientation from said axial direction at least adjacent the inner (7) and outer (5) defining walls of the gap (2) are effected by rotation of said defining walls preferably in opposed -directions. 10. A method as defined in claim 2, c h a r a ct e r¬ i z e d i n that material is advanced to said outlet in at least one closed passageway or the like located in a rotary body. 11. An apparatus for manufacturing extruded pipes, comprising devices for advancing plasticized material, for example plastic material, to an extrusion nozzle comprised in the apparatus, which nozzle comprises a circular gap, through which material is intended to pass -in axial direction, c h a r a c t e r i z e d i n that devices (5,7,9,14,15,20,21) are provided for mov¬ ing, for example rotating, material substantially in ' the circumferential direction of the gap (2), so that the material at least partially is caused to assume an orientation deviating from the axial direction, whereby non-axial orientation will prevail in the extruded pipe (3) and increase the strength. 12. An apparatus as defined in claim 11, c a r ¬ a c t e r i z e d i n that at least one outlet for material is provided which is located continuously or oscillating rotatable in the circumferential direction of the gap (2), and from which the material is intended to be supplied to a forming space (2' ) located at the outer end (4) of the extrusion nozzle. 13. An apparatus as defined in claim 11 or 12, . c h a r a c t e r i ze d i n that, at least one tub¬ ular body (9,14,15,20,21) is located rotatable in the gap (2), which body is intended for -moving material in the circumferential direction of the gap preferably at least adjacent the inner (7) and outer (5) defining wall of the gap (2), so that the material (5',7',17', 18' ) adjacent said defining walls (5,7) will be orient¬ ed in another direction than in certain intermediate portions (13',lβ') in the extruded pipe (3), and that said tubular bodies (9,1^,15,20,21) comprise at least one longitudinal slit (13,17,18,22,23) extending between a feed-in space (1') for the material and a forming space (2') located at the outer end (4) of the extrusi- 5 on nozzle. 14. An apparatus as defined in claim 13, c h a r a c t¬ e r i z e d ' i n that two pipes (14,15) are provided, one inner one (14) and one outer one (15), which join said inner (7) and, respectively, said outer (5) defin- T0 ing wall and are rotatable. preferably in opposed direct¬ ions and between themselves form a space (lβ) for subst¬ antially axial transport of material, and that each pipe (14,15) comprises at least one longitudinal slit (17,18) extending between a feed-in space (1') for the material 1 5 and said forming space (2'). 15. An apparatus as defined in claim 14, c h a r a c t¬ e r i z e d i n that said space (lβ) between the pipes (20,21) is very small or substantially non-exist¬ ing. 20 lβ. An apparatus as defined in claim 14 or 15, c h a r a c t e r i z e d i n that said outer pipe comprises recesses (19,24) in contact with said feed-in space (1') and the slit(s) (17,22) of said inner pipe (14,20), via which recesses (19,24) material is intend- 25 ed to be supplied to the slit(s) of the inner pipe. 17. An apparatus as efined in claim 13,14,15 or lβ, c h a r a c t e r i z e d i n that evices are prov¬ ided for adjusting and controlling the rotation speed " of said pipe (9,14,15,20,21), whereby said rotation 30 speed can be controlled in relation to the advancing speed of the material in said slit(s) (13,17,18,22,23) and whereby the distribution and size of said orientat¬ ion deviations partially can be controlled. 18. An apparatus as defined in claim 11, c h a r a c t¬ e r i z e d i n that said inner (7) and outer (5) defining walls are rotatable in the circumferential dir¬ ection of the gap (2), preferably in opposed directions. 19. An apparatus as defined in claim 12, c h a r a c t¬ e r i z e d i n that the material is intended to be advanced to said outlet in at least one closed passage¬ way or the like located in a rotatable body.

Inventors: DZIEWANOWSKI ANDRE, PIOTROWSKI KRZYSZTOF, ZAREMBA KRZYSZTOF, DZIEWANOWSKI, ANDRE, PIOTROWSKI, KRZYSZTOF, ZAREMBA, KRZYSZTOF
Applicants: DZIEWANOWSKI ANDRE, LUNDBERG MATS, PIOTROWSKI KRZYSZTOF, ZAREMBA KRZYSZTOF, DZIEWANOWSKI, ANDRE, LUNDBERG, MATS, PIOTROWSKI, KRZYSZTOF, ZAREMBA, KRZYSZTOF
Application year: 1984
Main classification: B29D23
IPC codes: B29C47