DEVICE FOR MAKING PIPINGS OF THERMOPLASTIC MATERIALS

Abstract: The invention concerns thermoplastic piping of complex profile used in mechanical construction and chemical indu­ stries, method of its production, equipment for its produc­ tion and equipment for its application. Piping made of thermoplastic resins is formed by the external and internal pipes which are mutually interconnec­ ted at least by one longitudinal partition wall. The prin­ ciple is that the external and internal pipes and partition walls are produced simultaneously as a monolithic profile. For the length of the piping holds the condition that the ratio of the pipe length to the largest diameter is larger than 600. The profile of the piping is shaped by the ex­ trusion head formed by the heated body in whose longitudi­ nal axis is by first distance spacers fixed an extruder co­ re. The principle is the core, fixed in the longitudinal axis of the extruder core by second distance spacers. The extruder core has at its outlet side formed longitudinal slots longer than 1/10 of the extruder core length. The out­ let side of the core is equipped by a towed bush with coo­ ling channels of the liquid and in the extruder core and core are formed cooling channels for gas. These pipings can be used for transport of liquids and gases in heat exchangers and transport units.

Description: The invention concerns the piping made of thermplas­ tic resin, used in mechanical and chemical industries, met­ hod of their production and equipment for their production and application. There are known thermoplastic profiles divided by par­ tition walls to several separated ducts, while neither of them is surrounded by other spaces on its whole circumfe­ rence. This arrangement is used for windows, furniture or facing profiles, but is not suitable in heat exchangers or for transport of one or several gases or liquids at defined thermal and pressure conditions. Other thermoplastic profi­ les are formed by the external (outer) and internal (inner) pipes which are along the whole pipe lengths connected at least by one longitudinal partition wall. These pipings can be produced in two ways. According to the first proce­ dure the external and internal pipes are formed separately and then in another operation the piping is completed by fixing the internal pipe into the external one. The parti­ tions are shaped simultaneously with the external or in­ ternal pipe. The length of pipes fixed one into the other is limited and is limiting the length of piping up to se­ veral tens of meters. For application where longer pipings are needed it is necessary to connect several pipes. Accor­ ding to the second method both the external and internal pipes are shaped successively in two extrusion heads situa­ ted one behind the other, while their mutual positioning is free. The length of so produced pipings is not limited. The disadvantage of this arrangement is small strength of these pipings which is limiting their use. There is a certain risc of deformation or undesired shift of the pipes. To reach the required strength it would be necessary to make the wall thicker which is considerably reducing the thermal conductivity. Mutual disadvantage of both these methods is the high product cost and only straight pipes can be pro­ duced in this way. The described disadvantages are avoided by use of pi­ pings made of thermoplastis, formed by the external and in­ ternal pipes which are mutually interconnected at least by one longitudinal partition wall and method of their produc­ tion according to this invention. The principle of this method is that the internal and external pipes and parti­ tion wall are produced simultaneously as one profile. For the length of such pipings holds the condition that the ratio of the length of the piping to the largest pipe dia­ meter should be larger than 600. The profile of the pipe is shaped by use of the extrusion head formed by a heating element, where in its longitudinal axis is by first solid distance spacers fixed the extruder core. The core is fi­ xed in the longitudinal axis by second distance spacers. The extruder core has at the outlet side longitudinal slots with the length larger than one tenths of the extruder core length. The outlet side of the core is equipped by towed bush with cooling channels of liquid media and in the ex­ truder core and core are formed cooling channels of the gas. These pipings can be used for transport of liquids and gases in heat exchangers and transport equipments. The advantage of the invention is first of all the si­ multaneous production of the whole piping profile, which means multifold reduction of the production cost. The method of production and design of the extrusion head enables sha­ ping of pipings made of thermoplasts e.g. by winding on a cylindrical support immediately behind the exit from the production line. These properties of pipings made of ther­ moplasts can be advantageously used as substitutes of metal pipings e.g. in heat exchangers. Lower thermal conductivity of thermoplastic materials is in this case well balanced by the possibility of use of real countercurrent flow which is not possible with metal pipes, or is costly and complex. Moreover there is a lower tendency to formation of scale. The result are better properties of these pipings. Cylindri­ cal arrangement of heat exchangers is compact and reduces the occupied space and base area, moreover due to its lower weight it is easier for transport. Pipings made of thermoplasts according to this inven­ tion can be also used for transport of gases and liquids, while the given profile enables simultaneous transport of several fluids or transport of only one fluid which is in­ sulated or cooled or heated. On attached drawings are in Figs 1 and 2 given examp­ les of two profiles of pipings made of thermoplastic resin according to this invention. In Fig. 3 is demonstrated the axial section of the extrusion head according to this in­ vention and in Fig. 4 is the cross section A-A through the extrusion head in its outlet part. The profile of piping made of thermoplasts is formed by the external pipe 1 , internal pipe 2 and longitudinal partition wall 3 . Shape and complexity of the profile is fixed by the extrusion head which forms the shaping part of the extrusion production line. The extrusion head con­ sists of the body 4 , equipped at its circumference by hea­ ting elements 9 , while in the axis of the extrusion head is by the first distance spacers 7 fixed the extruder core 5 . At the exit from the extruder core 5 is by second distan­ ce spacers 8 fixed the core 6 . To the core 6 is at the exit part of the extrusion head, e.g. by use of a thread 21 fi­ xed the towed bush 12 with cooling channels 10 of the li­ quid. These channels 10 are by the core 6 interconnected with the outside part of the body 4 . Similarly from the ex­ trusion head are led the cooling channels 11 of the gas which are terminated in the body of the extruder core 5 and core 6 . The external pipe 1 and internal pipe 2 of the piping made of thermoplastic resin are mutually interconnected at least by one longitudinal partition wall 3 . These partition walls 3 are usually three or four so that the piping is sufficiently strong. Usually the circular shape of the scross section of both pipes 1 , 2 can in generally have the shape of a polygon. At production of pipings of thermoplastic resins are into the storage tank of the extrusion line fed granular thermoplasts which are heated to the requested temperature. Molten thermoplast is by use of the screw conveyor pressed into the extrusion head in which it is flowing around the core 6 and extruder core 5 . Behind the spacers 7 , 8 which are situated at the inlet or not farther than middle part of the extrusion head the stream of the molten thermoplast is re-united and is forming a monolithic surface of the external and internal pipes 1 and 2 . Longitudinal partition walls 3 form in the outlet part of the extrusion head where the molten material is filling the longitudinal slots 14 formed in the extruder core 5 . The length of these slots must be equal at least to one tenth of the length of the extrusion head. The needed temperature of the melt in the extrusion head is reached by use of heating strips 9 . In­ ternal cooling takes place simultaneously both in the ex­ truder core 5 , core 6 and in the towed bush 12 as well, which serves also for callibration of the internal pipe 2 . Behind the extrusion head is the thermoplastic piping cooled usually in a liquid bath. Cooling channels 10 of the liquid formed in the towed bush 12 serve for cooling of the internal pipe 2 . By the gas leaving the core 6 a narrow layer is formed between the surface of the towed bush 12 and the internal pipe 2 which is reducing their friction. The gas phase leaving the ex­ truder core 5 is pressing the external pipe 1 to the calli­ bration cylinder and is simultaneously cooling the internal and external pipes 2 and 1 , inclusive the longitudinal par­ tition walls 3 . Moreover the gas due to its motion keeps the thermoplastic piping soft which is enabling its winding on the cylinder of the winding unit or other shaping. The cheap production of a monolithic profile of ther­ moplastic piping together with its technical parameters enables its use in heat exchangers and in units for trans­ port of one or several fluids. The heat exchangers can be formed of a thermoplastic pipe wound on a cylindrical sup­ port in one or several layers or by winding several paral­ lel pipes so as to achieve the most advantageous heat trans­ fer conditions. The transport equipment can be used for transport of warm or cold liquids through the internal pipe with thermal insulation e.g. by a gas which flows in the space in between both pipes, for transport of several fluids by one profile of the piping simultaneously or for keeping a constant temperature of the fluid flowing in the inter­ nal pipe and its heating or cooling by use of a fluid flo­ wing through other parts of the piping. The given properties of the piping according to the invention enable its use as thermally insulating cover of metal or other cylindrical objects such as cables in con­ struction as solid construction element of various shapes etc.

Claims: 1. Piping made of thermoplastic resin, formed by the exter­ nal and internal pipes mutually interconnected at least by one longitudinal partition wall, specified so that the external pipe (1), internal pipe (2) and longitudi­ nal partition wall (3) form a monolithic profile. 2. Piping made of thermoplastic material according to point 1, specified so that the ratio of the length of piping to the largest diameter is larger than 600. 3. Method of production of piping of thermoplastic resin consisting of the external and internal pipes and the baffle according to points 1 and 2, where the granular thermoplast is heated to the requested temperature within the range of 180 and 300°C, specified so that the exter­ nal and internal pipes and baffle are extruded as a mo­ nolithic profile. 4. Extrusion head for production of pipings of thermoplastic resin according to claims 1 and 3, formed by a heated bo­ dy in whose radial axis is by first distance spacers fi­ xed an extruder core, specified so that in the longitu­ dinal axis of the extruder core (5) which has at its outlet part formed longitudinal slots (14) longer than 1/10 of the length of the extruder core (5) and where by second distance spacers (7) is fixed the core (6) whose outlet side is equipped by a towed bush (12) and cooling channels (11) of the liquid while in the extruder core (5) and in the core (6) are formed cooling channels (10) of the gas. 5. Application of pipings made of plastic material accor­ ding to claims 1 to 4 for transport of liquids and gases in heat exchangers and transport units.

Inventors: CERVENKA, JAN, MASAK, VLADIMIR, NOVOTNY, JOSEF, RUICKA, FRANTISEK
Applicants: CESKOSLOVENSKA AKADEMIE VED
Application year: 1987
Main classification: F16L9
IPC codes: F28F21, B29C47, F16L9