Classifications

• • 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
  • B29C69/00—Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore
  • B29C69/02—Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore of moulding techniques only
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
  • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
  • B29C48/901—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies
  • B29C48/903—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies externally
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/05—Filamentary, e.g. strands
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/355—Conveyors for extruded articles
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/92—Measuring, controlling or regulating
• • 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
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92009—Measured parameter
  • B29C2948/92028—Force; Tension
• • 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
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92323—Location or phase of measurement
  • B29C2948/92428—Calibration, after-treatment, or cooling zone
• • 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
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92504—Controlled parameter
  • B29C2948/92523—Force; Tension
• • 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
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92819—Location or phase of control
  • B29C2948/92923—Calibration, after-treatment or cooling zone
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/06—Rod-shaped
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/12—Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
  • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
  • B29C48/904—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article using dry calibration, i.e. no quenching tank, e.g. with water spray for cooling or lubrication
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
  • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
  • B29C48/908—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article characterised by calibrator surface, e.g. structure or holes for lubrication, cooling or venting
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
  • B29C48/911—Cooling
  • B29C48/9135—Cooling of flat articles, e.g. using specially adapted supporting means
• • 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
  • B29K2071/00—Use of polyethers, e.g. PEEK, i.e. polyether-etherketone or PEK, i.e. polyetherketone or derivatives thereof, as moulding material
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber

Definitions

• the invention relates to an extrusion plant for the production of cylindrical semi-finished plastic products according to the preamble of claim 1.
• thermoplastics such as polyetheretherketone (PEEK) should be mentioned here.
• extrusion plant which is suitable for the production of cylindrical semi-finished products from thermoplastic, polyolefin-based mass plastics is described in WO 1998/09709 A1. It comprises a known, heated screw extruder, which melts the filled in granular plastic. By an extrusion die, the melt exits and the resulting endless strand receives its coarse cross-section. In a downstream calibration section of the plastic strand is cooled and receives the desired external dimensions. Downstream of the calibration is a braking device comprising two rolls of polyurethane rolling on the freshly calibrated strand. The rollers are pressed by a spring-loaded lever system against the strand to a clean unwinding allow.
• the rotatably mounted in the levers rollers are provided with a non-descript pneumatic brake. This makes it possible to decelerate the rollers on their respective axes of rotation and thus initiate a directed against the advance of the plastic strand axial force in the plastic strand.
• This axial force increases the back pressure in the strand section between the extrusion tool and the braking device and thus ensures a particularly high material density in the extrudate.
• the axial force is measured by a force transducer and guided in a control device. This generates a braking force in the braking device as a function of the measured axial force. In this way, the axial force is regulated.
• Another disadvantage of the known extrusion plant is that it is not suitable for the processing of plastics having a high melting point: polyolefins such as PP and PE are extruded at about 200 ° C, the temperature of the plastic strand after passing through the cooling calibration is still about 32 to 60 ° C (90 to 140 F). At these low temperatures, the PU wheels of the braking device still run without sticking on the strand.
• PEEK is a high-temperature thermoplastic whose melt exits the extrusion die at about 400 ° C. After calibration, the temperature of the PEEK is still well over 100 ° C, so that would be to get in the known system that the PU wheels of their braking device, the thermal and mechanical load not withstand and damage the plastic strand.
• the invention is based on the object to form an extrusion plant of the type mentioned so that they have a achieved better control quality and is suitable for the processing of high-temperature plastics.
• the invention therefore relates to an extrusion plant for the production of cylindrical semi-finished plastic, with an extruder for providing a pressurized melt of the plastic, with at least one extrusion die arranged on the extruder, through which the melt emerges from the extruder as a substantially cylindrical plastic strand , with a downstream of the extrusion die, cooled by the freshly extruded plastic strand calibration, which cools the plastic strand and imparting an outer diameter, with a calibration downstream braking device by means of which in the plastic strand a thrust directed against its axial force is variably introduced, and with a Force transducer, which measures the introduced from the braking device in the plastic strand axial force, wherein the braking device at least one movable radially to the plastic strand, with a Re
• the radially movably guided brake shoe can be acted upon by a radial force on the friction surface abutting the circumference of the plastic strand, and wherein the friction surface has
• the inventively designed, radially movable brake shoe with its groove-shaped friction surface fulfills a dual function: It sets the radial force directly over a short, rigid path in the friction force corresponding axial force, so on the friction coefficient between the friction surface and strand a simple proportional relationship between the applied radial force and the axial force to be controlled arises. This allows a fast and accurate control.
• the surface contact allows heat flow from the strand in the brake shoe, which - correspondingly voluminous dimensioned - serves as a heat sink. Overheating of the friction surface is therefore excluded, which is why it can be operated at higher temperatures.
• the inventive design of the braking device thus solves two technically very different tasks compared to the prior art.
• a preferred embodiment of the invention is that the braking device comprises a second, radially fixed, provided with a Jacobreib simulation brake shoe in addition to the first, movable brake shoe, wherein the Gegenreib simulation has the shape of a groove-shaped cutout of a cylinder jacket.
• the basic idea of this development is to drive the movable brake shoe against an immovable jaw. Compared to two mutually moving brake shoes, this embodiment has the advantage that the radial force can be determined more accurately about the position of the jaw, since the current position of a movable counter-jaw does not have to be considered. This benefits the control quality.
• the braking device is preferably designed in such a way that the friction surface and the counter-friction surface in an end position of the radially movably guided brake shoe complement one another to form a cylinder jacket comprising the plastic strand. In this way, the radial force is introduced via a particularly low surface pressure in the strand, so that its calibrated shape remains unchanged.
• the invention is not restricted to circular-cylindrical designs:
• the shape of the friction surfaces according to the invention can also be correspondingly elliptical or polygonal.
• all cylinders are preferably circular cylinders.
• the radius of the friction surface and / or the counter-friction surface is smaller than half of the outer diameter impressed on the plastic strand by the calibration. Through a minimal undersize the axial force is introduced particularly evenly and gently into the strand.
• the friction surfaces are preferably made of copper-containing materials such as brass, gunmetal or bronze. These non-ferrous materials provide good heat dissipation so that plastics with high processing temperatures can be extruded on the equipment, such as preferably polyetheretherkethone.
• the extrusion system according to the invention is equipped with a pneumatic, by means of which the radially movable guided brake shoe in the direction of the plastic strand can be acted upon.
• the pneumatic allows a high control dynamics, as pneumatic cylinders can act on the radially movable guided brake shoe with a rapidly increasing or decreasing pressure or relieve.
• the braking device is arranged on the carriage of a parallel to the plastic strand extending linear guide, so stored axially displaceable, and arranged the force transducer between the carriage and the immovable frame of the extrusion plant.
• This design ensures that the force transducer is always loaded parallel to the axial force and that due to the low friction losses within the linear guide, the force measured in the force transducer largely corresponds to the axial force. This gives good measured values, which are prerequisites for a high quality of control.
• a pressure-loaded load cell is used as a load cell, which faces in the feed direction of the plastic strand on the front side of the carriage, a stop located on the frame of the extrusion system, is arranged.
• This design has proven to be particularly practical during operation and when retrofitting the extrusion line to other extrusion tools.
• the constant retention of the back pressure in the plastic strand is preferably carried out by a control loop, within which the axial force represents the controlled variable and the radial force is the manipulated variable.
• the radial force can namely be made significantly more dynamic thanks to the braking device, so that the braking device allows a much better control than is the case with known control concepts in which the keep constant the back pressure the speed of the screw or the speed of a trigger system is used as a manipulated variable.
• the control circuit preferably has a controller with combined proportional, differential and integral control characteristic (PID).
• PID proportional, differential and integral control characteristic
• the extrusion system according to the invention is outstandingly suitable for the production of cylindrical semi-finished products made of heat-resistant plastic and in particular for the production of circular-cylindrical solid rods of polyetheretherketone. These uses are therefore also subject of the invention.
• Figure 1 Schematic representation of the extrusion plant in side view
• FIG. 2 enlargement of FIG. 1 in the region of the braking device
• FIG. 3 end view of the braking device
• FIG. 4 Perspective representation of the counter friction surface.
• the extrusion system comprises inter alia an extruder 1, a calibration 2 and a braking device 3. These assemblies are arranged coaxially along the linear extrusion direction E.
• the extruder 1 is a screw extruder, a machine known in the processing of thermoplastics.
• the extruder receives the thermoplastic raw material in the form of granules in a hopper 4.
• a screw 5 surrounded by a heater, which conveys the granules under the action of heat in the direction of extrusion E and pressurizes them.
• Downstream of the screw 5 is a storage chamber 6, in which the plastic is present in a pressure-loaded melt.
• the temperature in the extrusion of the high temperature thermoplastic polyetheretherkethon is here about 400 0 C, the optimal dynamic pressure is in the extrusion of PEEK solid rods about 5 bar.
• the stagnation chamber 6 Downstream, the stagnation chamber 6 is limited by a per se known extrusion tool 7. It has a circular opening from which the melt emerges as a circular cylindrical, endless plastic strand 8.
• extrudate forms are also cylinders.
• the invention is therefore not limited to circular cylindrical shapes.
• An installation according to the invention can also comprise an extrusion tool with a plurality of openings, so that a plurality of parallel extrusion strands arise there. The plant components described below would then be present multiple times and arranged parallel to each other. For the sake of simplicity, an extrusion plant with a single plastic strand 8 will be described, which is extruded in Extrusionshechtung E.
• the freshly extruded plastic strand 8 preformed through the opening of the extrusion die 7 first enters the calibration 2.
• the calibration known per se is, in simplified terms, a cylindrical, cooled tube with a defined inner diameter.
• the inner diameter of the tube is impressed on the plastic strand 8 as outer diameter d.
• the plastic strand 8 is cooled so that the melt solidifies.
• the temperature of the PEEK plastic strand is about 100 ° C.
• the braking device 3 Downstream of the calibration 2 is the braking device 3.
• the function of the braking device 3 is to initiate a change in the direction of extrusion E or the advance of the plastic strand 8 opposite axial force A in the plastic strand 8 variable in terms of their amount.
• This axial force A is able to increase the pressure within the plastic strand 8 between its exit from the extrusion die 7 and the braking device 3, ie in particular in the area of the cooling calibration.
• the pressure within this section of the plastic strand 8 has a significant influence on the dimensional stability of the extrudate: Since thermoplastic plastics shrink on cooling, it is necessary enough Specify material to compensate for the shrinkage. A high dimensional stability and material density is therefore determined by the correct dynamic pressure in the area of the calibration 2, which according to the invention is set via the axial force A generated by the braking device 3. The operation of the braking device 3 will be explained later.
• the introduced by the braking device 3 in the plastic strand 8 axial force A is measured by means of a force transducer 9 in the form of a pressure-loaded load cell.
• the braking device 3 is arranged on the carriage 10 of a parallel to the Extrusionshchtung E or plastic strand 8 extending linear guide 11, so that the braking device 3 is axially freely displaceable.
• the mobility of the carriage 10 is limited by a stop 12, which is part of the immovable frame 13 of the extrusion plant.
• the load cell 9 Arranged at the front side on the carriage 10 is the load cell 9, with which the carriage 10 bears against the stop 12 under load.
• the carriage 10 is taken along until it bears against the stop via the load cell 9. Due to the parallel alignment of the linear guide 11 to the extrusion direction E, the force measured in the force-measuring box 9 clamped between the stop 12 and the slide 10 is aligned parallel to the axial force A. Since the friction within the linear guide 11 is very low, the force measured in the load cell 9 corresponds almost to the axial force A. The load cell 9 thus provides a measured value which corresponds to the magnitude of the axial force A to be measured to an outstanding degree.
• the calibration 2 is likewise guided axially displaceably to the strand 8 by means of a second carriage 14 on the linear guide 11 and the linear guide 11 is mounted directly in the extrusion tool 7 on the extruder side.
• a high coaxiality of extrusion tool 7, calibration 2 and braking device 3 is achieved, whereby the plastic strand 8 can be manufactured with low dimensional tolerances.
• Downstream of the braking device 3 is a per se known, with the feed of the plastic strand 8 synchronized roller take-off 15.
• the downstream can be further system components such as a cooling and / or vacuum line or a Be cutaway device. Since such devices are generally known in extrusion plants, they need not be explained in detail here.
• the traversed by the plastic strand 8 brake device 3 comprises two brake shoes 16, 17.
• the first brake shoe 16 is guided radially movable plastic strand 8, the second brake shoe 17 radially immovable.
• the radial mobility of the brake shoe 16 to the fixed brake shoe 17 is ensured by a radial guide 18 which is fixed in the radially immovable brake shoe 17 and on which the radially movable brake shoe 16 slides.
• the position of the movable brake shoe 16 relative to the fixed brake shoe 17 is adjusted by a pneumatic, not shown, which comprises an actuator by means of which the movable brake shoe 16 can be moved.
• the association of the two brake shoes 16, 17 is a total of the plastic strand 8 axially displaceable, since the radially fixed brake shoe 17 rests directly on the carriage 10 of the linear guide 11.
• Both brake shoes 16, 17 have on their plastic strand 8 side facing a friction surface 19 and a Jacobreib Status 20 on.
• the friction surfaces 19, 20 in the brake shoes 16, 17 are each formed by a brass insert, which has the shape of a groove-shaped section of a cylinder jacket. This shape is obtained by halving a cylindrical, thin-walled tube in the longitudinal direction.
• the radius r of both friction surfaces 19, 20 is equal and slightly smaller than half the diameter d of the outer diameter of the plastic strand 8, which was impressed him by the calibration 2 .
• the movable brake shoe 16 is movable up to an end position against the immovable brake shoe 17, in which the two friction surfaces 19, 20 complement one to the plastic strand 8 comprehensive cylinder jacket. Due to the slight undersize of the friction surfaces 19, 20, a surface contact between the brake shoes 16, 17 and the plastic strand 8 takes place, so that the surface pressure is low. An undue stress entry into the extrudate is therefore avoided. A minor injury to the strand is harmless since the semi-finished product is still processed further by machining.
• the optimal back pressure of about 5 bar within the cooling extrudate is adjusted via the axial force A, which introduces the braking device 3 in the plastic strand 8.
• the pneumatic actuator actuates the movable brake shoe 16 with a radial force R directed in the direction of the fixed brake shoe 17.
• the strand 8 is pressed between the friction surface 19 and the counter friction surface 20, so that a friction force proportional to the radial force R is produced at the friction surfaces 19, 20. as opposed to the feed of the plastic strand 8 axial force A results.
• the radial force R is controlled so that the axial force A is variable by means of the braking device 3 in terms of their amount.
• the axial force A is measured very accurately as already described on the load cell 9.
• a not drawn loop keeps the axial force A and thus the back pressure in the plastic strand 8 constant.
• the control circuit receives the axial force actual value measured by the force transducer 9, constantly compares this with a preset axial force setpoint and adjusts the radial force R accordingly via the pneumatic system in order to equalize the axial force actual value to the axial force setpoint. If the axial force is too low, the radial force R is increased by stronger tightening of the movable brake shoe 16; If the dynamic pressure in the extrudate is too great, the air pressure in the actuator is lowered. Consequently, the axial force A within the control loop is the controlled variable X, during which the radial force R acts as a manipulated variable Y.
• the regulation takes place via a PID controller.
• the adjustment of the radial force R is much more dynamic than adjusting the screw speed or changing an impressed withdrawal speed, both of which is a standard in the art control approach. Nevertheless, the control according to the invention can be combined via the radial force R with the classic regulation via screw speed and take-off speed as manipulated variables. LIST OF REFERENCE NUMBERS

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Braking Arrangements (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=42309046

Family Applications (1)

Country Status (9)

Families Citing this family (8)

Family Cites Families (11)

• 2009
  • 2009-07-09 DE DE102009032287A patent/DE102009032287A1/de not_active Withdrawn
• 2010
  • 2010-01-18 CN CN2010800054410A patent/CN102292205A/zh active Pending
  • 2010-01-18 RU RU2011134611/05A patent/RU2011134611A/ru not_active Application Discontinuation
  • 2010-01-18 KR KR1020117019270A patent/KR20110117186A/ko not_active Application Discontinuation
  • 2010-01-18 WO PCT/EP2010/050509 patent/WO2010084094A2/de active Application Filing
  • 2010-01-18 BR BRPI1006868A patent/BRPI1006868A2/pt not_active IP Right Cessation
  • 2010-01-18 EP EP10701495A patent/EP2379302A2/de not_active Withdrawn
  • 2010-01-18 JP JP2011546763A patent/JP2012515669A/ja not_active Withdrawn
  • 2010-01-18 US US13/143,351 patent/US20110274923A1/en not_active Abandoned

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