EXTRUSION DEVICE, EXTRUDER AND METHOD FOR SHEATHING WIRES, CABLE PREPRODUCTS OR STRANDS

Description

[0001] The invention relates to an extrusion device for sheathing wires, cable precursors, or stranded wires. The extrusion device comprises an extrusion head with a precursor guide and a forming die. The precursor guide and the forming die are arranged relative to one another in such a way that a molding compound can be formed into an extruded shaped piece through an opening in the precursor guide. Furthermore, the invention relates to an extruder and a method for sheathing wires, cable precursors, and stranded wires.

[0002] Extrusion typically involves continuously forcing solid to liquid curable compounds under pressure and / or elevated temperature through a die into a long molded part using a nozzle. Extrusion is used, for example, to coat wires, pre-finished cable products, and stranded wires, with the coating made from the molding compound being applied to the wires, pre-finished cable products, or stranded wires.

[0003] During extrusion, even the slightest differences in temperature and / or pressure and the need to manufacture to very tight tolerances often mean that the first 200 m to 500 m of coated wires, cable precursors or strands have to be disposed of as waste.

[0004] During extrusion, it is particularly important that the opening of the preform guide is optimally aligned with the forming die. Furthermore, the sheathing must be radially homogeneous around the wire, cable preform, or strand and aligned with the centering and longitudinal axes.

[0005] When sheathing electrical conductors (wires and strands), the centering of the pre-product guide and / or the forming die is usually performed manually. The forming die is aligned using a centering plate, which is mounted on the extrusion head with the pre-product guide. Screwed positions on the centering plate tilt the centering plate and thus the forming die. Due to the limitation to tilting and manual adjustment, the alignment of the pre-product guide and the forming die is not precise enough to achieve the required, very tight manufacturing tolerances.

[0006] From DE 692 11 772 T2 (EP 0 513 616 81) an extrusion device for sheathing wires, cable precursors or strands is known, wherein the extrusion device has an extrusion head with precursor guide and a forming die.

[0007] Servomotors, by means of whose movements two centering devices can be aligned with each other, are known from US 5 795 531 A. Furthermore, a method is disclosed in which a continuous wire is introduced into the extrusion head.

[0008] US 4 551 087 A discloses a method for comparing the determined thickness with a target thickness of an insulation layer, wherein the thickness of the insulation layer can be changed by means of adjustment tools on an extrusion device.

[0009] From DE 10 2008 061 286 A1 an extrusion device for producing tubular hollow bodies or casings is known, which has an adjustable positionable mouthpiece in the area of ​​an extruder nozzle.

[0010] A device having an extruder head having a nozzle, an inlet nozzle and an outlet nozzle for passing an electrical conductor through and encasing the electrical conductor with an insulating layer is known from US 4 668 173 A.

[0011] DE 87 04 664 U1 discloses a device with a centering device for producing pipes, wherein the centering device has movable wedges and a measuring device is associated with the device which checks the wall thickness distribution.

[0012] JP 2009 166244 A describes an extrusion device for sheathing an electrical cable, in which the extrusion die surrounds the pre-product guide within a crosshead main body, and the extrusion mass is guided through a gap between the extrusion die and the pre-product guide. For centering, the extrusion die is surrounded by four rotatable connecting elements, each of which is rotatably attached to the crosshead main body via a rotating shaft. An adjustment screw can act on the opposite ends of each of which is guided through a bore in the crosshead main body. Instead of the adjustment screws arranged off-center to the extrusion die for effecting the rotational movements of the connecting elements, drives operated by electrical, pneumatic, or hydraulic pressure are also proposed.JP S6071221 A discloses stator motors as drive sources which rotate the adjusting screws of a mold.

[0013] From DE 10 2014 103 101 A1 a device is known which is suitable for the production of blow-molded hollow plastic bodies, wherein tubular preforms are extruded simultaneously from several extrusion tools of a multiple extrusion head arranged next to one another and are fed to blow mold cavities of a closing unit.

[0014] US 2002 / 158357 A1 discloses an extrusion device in which a mold with a round surface along its longitudinal axis is surrounded by a mold holder, fitting snugly in a round receptacle. The position of the mold can be adjusted by means of two adjusting screws arranged at right angles to each other in the mold holder, with the adjusting screws pushing or pulling the mold holder along two different perpendicular lateral directions. Instead of the adjusting screws, the position of the mold can also be adjusted by installing electrical drive devices, such as piezoelectric actuators.

[0015] The object of the invention is to improve the state of the art.

[0016] The object is achieved by an extrusion device for sheathing wires, cable precursors or strands, wherein the extrusion device has an extrusion head with a precursor guide and a forming die, wherein the precursor guide and the forming die are arranged relative to one another in such a way that a molding compound can be formed through an opening in the precursor guide through the forming die to form an extruded molded part, and a motorized actuating device is assigned to the precursor guide and / or the forming die, wherein the motorized actuating device has a piezo actuator and the piezo actuator is arranged on the precursor guide and / or on the forming die, so that when an actuating signal is applied to the motorized actuating device, the precursor guide and the forming die can be aligned relative to one another by means of a direct linear movement of the piezo actuator.

[0017] By aligning the pre-product guide and the forming die with each other using the motorized adjustment device, finer adjustment is possible, resulting in better centricity values ​​and thus better product properties. Furthermore, product quality is more reproducible.

[0018] It is particularly advantageous that the pre-product guide and the forming die can be aligned more quickly, both during start-up and in the event of changes in production parameters or malfunctions. This reduces material consumption, rejects, and the amount of waste (scrap) to be disposed of.

[0019] By applying the control signal, a very precise, automatic centering of the extrusion head and / or the forming die is possible.

[0020] Another advantage over the prior art is that a tiltable centering plate for a front head of the extrusion head is eliminated, and the motorized actuator itself and / or the front head no longer necessarily need to be fixed in place, but can be arranged separately, for example, on a movable rail. This provides better accessibility to the actuator and / or the front head and improved interchangeability.

[0021] An essential idea of ​​the invention is that by applying an actuating signal to the motorized actuating device, a very defined and fine alignment of the pre-product guide and the forming die to each other takes place by means of a movement of the motorized actuating device caused thereby.

[0022] It is particularly advantageous that there is a direct linear proportionality between the applied control signal and the actuating movement of the motorized actuating device.

[0023] The following terminology is explained:

[0024] An "extrusion device" is, in particular, a device for extruding a molding compound through a precursor guide and a forming die to form an extruded molded part. An extrusion device is, in particular, a device for sheathing wires, cable precursors, or strands. An extrusion device is used, in particular, for cold, warm, and / or hot extrusion. The extrusion device operates, in particular, at a pressure of 10 bar to 1500 bar and a temperature of 10 °C to 500 °C. However, an extrusion device can also be, in particular, a device for pipe, profile, and / or film extrusion, as well as for extrusion molding. An extrusion device has, in particular, an extrusion head, a precursor guide, a forming die, and / or a separate or integrated pre-head to the extrusion head.An extrusion device can in particular also be the extrusion head itself, which, in addition to the pre-product guide, also has the forming die.

[0025] A "wire" is, in particular, a thin, long, and / or flexible metal with a circular cross-section. A wire can also be flat, square, or profiled. A wire is, in particular, made of copper, aluminum, or a copper alloy.

[0026] A "stranded wire" is an electrical conductor consisting of thin individual wires and is particularly easily bendable. To distinguish it from inflexible single-wire and / or multi-wire conductors, a stranded wire is also referred to as a fine-wire or ultra-fine-wire conductor. In high-frequency stranded wires, the individual wires are insulated from each other, particularly by a layer of varnish. A stranded wire is typically made of copper. The individual wires of the stranded wire are generally enclosed by a common insulating sheath (stranded wire). If several stranded wires are combined in a cable, these are called cores. A stranded wire has a thickness of 0.004 mm to 4 mm.

[0027] A "core" is, in particular, a single conductor within a cable bundle. A core is typically an insulated wire or strand. A single- or multi-core composite of cores sheathed with insulating materials forms, in particular, a "cable precursor." A core has, in particular, copper, aluminum, silver, steel, and / or lead as its conductor material. A core has, in particular, a thickness of 0.1 mm to 15 mm.

[0028] "Sheathing" refers specifically to the extrusion (molding) of a sheath around the outside of a wire, a pre-finished cable, or a stranded wire. Sheathing serves primarily to insulate and / or shield the wire, pre-finished cable, or stranded wire. Plastics such as polyolefins, polyurethane, polyvinyl chloride, polytetrafluoroethylene (PTFE), and / or silicone are used as molding materials for sheathing.

[0029] An "extrusion head" is, in particular, a component that receives the flowable molding compound under pressure and feeds it to the precursor feeder via flow channels. At the same time, an extrusion head can, in particular, receive a continuous precursor material, such as a wire, precursor cable, or stranded wire. In addition to the precursor feeder, an extrusion head can also, in particular, have a forming die, or the forming die is assigned to the extrusion head. In particular, one or more extruders and / or one or more conveyor units for feeding the molding compound are arranged in the extrusion head.

[0030] A "precursor guide" is, in particular, a nozzle with an opening through which, in particular, a wire, cable precursor, or strand is continuously fed and / or the molding compound is continuously pressed (extruded). A nozzle is, in particular, a tapered tubular technical device with an opening at the smallest tapered cross-section. A precursor guide is, in particular, also a confuser. A precursor guide can be an extrusion nozzle.

[0031] A "molding die" is, in particular, a tool that imprints a shape on the molding compound leaving the precursor feeder. A molding die is also referred to as a die. The molding compound flows, in particular, through the interior of the molding die, filling the inner shape of the molding die. In the case of continuous precursor material such as wires, precursor cables, or strands, this is guided centrally through the molding die, with the molding compound encasing the outer surface of the precursor material and, as the outer surface, taking on the shape of the inner surface of the molding die.

[0032] A "motorized actuator" is, in particular, an actuator that is related to movement. A motorized actuator is, in particular, a device that executes and / or generates a movement. A motorized actuator, in particular, executes a linear extension and / or movement. In a motorized actuator, the length of the linear movement (actuating path) is, in particular, proportional to an applied actuating signal. A motorized actuator is, in particular, a linear motor, eccentric, spindle adjustment, and / or a piezo actuator.

[0033] A "control signal" is understood to mean, in particular, an electrical or pneumatic signal. A control signal is, in particular, a standardized, standardized signal, for example, a current signal from 0 mA to 20 mA or a voltage signal from 0 V to 10 V. Applying the control signal to the motorized control device induces, in particular, a defined movement of the motorized control device. The control signal can be applied manually and / or automatically. For example, by manually turning a rotary knob with step scaling, the control signal can be increased gradually, thus gradually lengthening the movement of the motorized control device. Likewise, the control signal can be applied automatically via a control and / or regulating device of the extrusion device and / or an external device.

[0034] A "movement" is, in particular, a linear movement or a movement along a curved path of the motorized actuator, which in turn sets a driven object, such as the forming die and / or pre-product guide, in motion. A movement is, in particular, a change in the location of the motorized actuator and / or the pre-product guide and / or the forming die.

[0035] "Alignment" refers, in particular, to the spatial arrangement of the precursor guide and the forming die relative to one another, so that a molding compound is optimally formed into an extruded part through the opening of the precursor guide and the subsequent forming die. Alignment also includes, in particular, centering, which involves alignment to the center point or central axis (centering axis) of components. In particular, the precursor guide and the forming die are centered relative to one another in such a way that a low eccentricity (as a measure of the deviation from the circular shape) of a finished formed part and / or a coated wire, cable precursor, or stranded wire is maintained.

[0036] In a further embodiment, the extrusion device has a receiving device for receiving a continuous pre-material, in particular a wire, cable pre-product or a strand, so that the pre-material can be coated with the molding compound.

[0037] This allows not only an optimal alignment of the pre-product guide and the forming die to each other, but also their alignment in relation to a picked-up, continuous pre-material.

[0038] Consequently, optimal wire, strand, core, sheath and / or cable extrusion can be achieved.

[0039] According to the invention, the motorized actuating device is arranged on the pre-product guide and / or on the forming die.

[0040] This allows for free positioning of the motorized actuator for aligning the pre-product guide and / or the forming die. The motorized actuator acts directly on the pre-product guide and / or the forming die.

[0041] In order to generate a defined linear movement, the motorized actuator has a piezo actuator.

[0042] Thus, the electrical energy of the control signal is directly converted into a mechanical, linear length extension and / or a linear movement in the nanometer range by means of the piezo actuator.

[0043] In addition, when using a piezo actuator, production at high temperatures can be realized without compromising product quality due to its temperature resistance of up to 250 °C.

[0044] A "piezo actuator" is, in particular, a component that utilizes the piezoelectric effect to execute a mechanical movement by applying an electrical voltage. A piezo actuator is, in particular, a piezo stack in a sandwich design. A piezo actuator, in particular, comprises a piezo ceramic. The piezo stack of a piezo actuator is usually housed in a housing, with a preload applied between the housing and the piezo ceramic to prevent tensile forces from the driven object. A piezo actuator, in particular, has a guide, for example, a flexible solid-state guide. A piezo actuator causes movement, in particular, through its longitudinal expansion.

[0045] In order to enable quick and flexible alignment in different spatial directions, the motorized actuating device has a second piezo actuator, a third piezo actuator, a fourth and / or piezo actuators.

[0046] This means that several movements from different directions can be used simultaneously to align the pre-product guide and the forming die.

[0047] A second, third, fourth and / or further piezo actuator corresponds to the piezo actuator defined above, wherein each individual piezo actuator is arranged at a different position in the extrusion device.

[0048] In a further embodiment of the extrusion device, the piezo actuator or the piezo actuators have or have a travel in the range from 0.01 nm to 1 mm, preferably from 0.1 nm to 200 µm.

[0049] As a result, very precise and fine adjustment of the alignment of the pre-product guide and / or the forming die can be achieved. This allows for very tight manufacturing tolerances of ± 0.05 mm, thus improving product quality.

[0050] A "travel distance" is in particular the change in length of a piezo actuator or the displacement of a linear motor or eccentric.

[0051] In order to enable continuous alignment and adjustment of the alignment of the pre-product guide and the forming die during production, a measuring device for determining at least one measured variable of an extruded shaped piece and / or a control and / or regulating device is or are assigned to the extrusion device, so that the actuating signal can be applied to the motorized actuating device depending on the determined measured variable.

[0052] This allows, for example, the actual centricity value of the fitting or the applied sheath of the sheathed wire, cable pre-product or strand to be continuously recorded and used to control and / or regulate the motorized actuating device.

[0053] It is particularly advantageous that the outer diameter, ovality, wall thickness and eccentricity as well as the inclination of a coated wire, cable pre-product or strand can be determined and that these parameters can be corrected directly during production by means of the extrusion device and / or the control and / or regulating device.

[0054] Consequently, eccentricity can be prevented from "running away" during production and long-term vibrations can be compensated.

[0055] A "measuring device" is, in particular, the entirety of all measuring instruments and additional devices for achieving a measurement result. A measuring device comprises, in particular, one or more measuring instruments designed to measure a measurand. A measuring device and / or a measuring device comprises, in particular, a sensor. A measuring device is, in particular, an online measuring device for the non-contact and continuous measurement of conductors, wires, stranded wires, and / or cables. The measuring device performs, in particular, an eight-point eccentricity, four-axis diameter, and / or eight-point ovality measurement. The measuring device comprises, in particular, two optical measuring instruments and an inductive measuring instrument for measuring the concentricity of a wire, cable precursor, or stranded wire in the insulation (sheath) and the product parameters of outer diameter, ovality, and wall thickness.In addition, the measuring device detects in particular an inclined position of the wire, cable pre-product or strand in a measuring plane and thus to the centering axis of the extrusion device.

[0056] A "control device" is, in particular, a device in which one or more variables as input variables influence other variables as output variables based on system conditions. A control device is, in particular, a device that intentionally influences the behavior of the extrusion device. In particular, the control device sends a control signal to the motorized control device.

[0057] A "control device" is, in particular, a device in which a variable is continuously recorded as a controlled variable, compared with another variable as a reference variable, and influenced depending on the result of this comparison to adjust to the reference variable. A control device, in particular, uses a closed control loop. When using a control device, in particular, the setpoint value, for example, the specified eccentricity, is compared with the measured actual eccentricity value of the measuring device (controlled variable). Based on the deviation from the setpoint value, a control signal is applied from the control device to the motorized control device in order to optimize the alignment of the pre-product guide and / or the forming die and thus achieve the setpoint eccentricity of a manufactured wire or strand.

[0058] A "measured quantity" is, in particular, the physical quantity to which a measurement applies. The measurand was or is, in particular, the target of a measurement. The measurand does not have to be the direct object of the measurement, but can also be determined from one or more quantities using physical and / or mathematical principles. The measurand is, in particular, a physical property of the extruded fitting or the coated wires, cable precursors, or strands. The measurand is, in particular, the diameter, ovality, wall thickness, concentricity, skew, and / or bending position of a wire, cable precursor, or strand.

[0059] In a further aspect of the invention, the object is achieved by an extruder for sheathing wires, cable precursors or strands, wherein the extruder has a previously described extrusion device.

[0060] Thus, an extruder is provided with optimal control and / or regulation of the extrusion process and for producing improved product properties through more precise centricity values ​​or other desired product parameters.

[0061] Above all, the extruder enables a reproducible quality of the extruded fittings and coated wires, cable pre-products or strands to be achieved.

[0062] An "extruder" is, in particular, a production device for extrusion. An extruder is, in particular, a piston extruder or a screw extruder with one, two, or more screw shafts. In addition, an extruder comprises, in particular, a drive, an extrusion head with a pre-product guide, a forming die, a pre-head, and / or a measuring device.

[0063] In an additional aspect of the invention, the object is achieved by a method for sheathing wires, cable precursors or strands by means of a previously described extrusion device with a previously described measuring device and / or a previously described control and / or regulating device and / or a previously described extruder, with the following steps: Inserting a continuous wire, cable pre-product or a continuous strand into the extrusion head, extruding the molding compound through the pre-product guide and the forming die to form a coated wire, cable pre-product or a coated strand, determining at least one measured variable of the coated wires, cable pre-products or the coated strand by means of the measuring device, using the determined measured variable to generate the actuating signal, regulating and / or controlling the motorized actuating device by applying the actuating signal, moving the motorized actuating device against the pre-product guide and / or the forming die, aligning the pre-product guide and / or the forming die to one another and dispensing a centered coated wire, cable pre-product or a centered coated strand.

[0064] Thus, in particular, a method for sheathing wires, cable precursors or strands is provided, in which at least one product property of the manufactured sheathed wire, cable precursor or strand is recorded online and / or continuously, and then the manufacturing process is adapted and optimized in terms of the manufactured product quality by aligning the precursor guide and the forming die to one another.

[0065] Thus, this manufacturing process not only enables higher product quality but also reduces material consumption, scrap, and waste. Furthermore, disruptions to the manufacturing process can be immediately detected and compensated for.

[0066] In the following, an extrusion device not according to the invention with conventional control via an alignment body is described.

[0067] It shows Figure 1 a highly schematic sectional view of an extrusion device with extrusion head, pre-product guide, mouthpiece and centering device.

[0068] An extrusion device 101 has an extrusion head 103 with a head housing 105 and an internal pre-product guide 107. A pre-head 109 is arranged on the extrusion head 103.

[0069] The front head 109 has a centering device 113. The centering device 113 comprises a mouthpiece 111, an alignment ring 115, and four piezo actuators 117. The four piezo actuators 117 are arranged at a distance of 90° from each other on the outside of the alignment ring 115 (for reasons of clarity, the two piezo actuators that protrude into and out of the image plane are not shown).

[0070] A centering axis 119 is assigned to the extrusion device 101. A measuring device (not shown) for measuring centricity is arranged behind the extrusion device 101. Furthermore, the extrusion device 101 includes a control device (not shown).

[0071] The following operations are performed with the extrusion device 101: A strand with an outer diameter of 0.25 mm is introduced into the extrusion head 103 and continuously passes through it and the die 101. Flowable polyethylene (PE) is pressed through the pre-product guide 107 and the die 111 at a temperature of 220 °C and a pressure of 300 bar, coating the strand.

[0072] Using the measuring device (not shown) (Centerview 8000 from Sikora), the centricity of the manufactured coated strand is determined online and continuously. The measurement shows that an eccentricity compensation of 1.15 (maximum sheath thickness to minimum sheath thickness) is necessary. A control signal is then generated by the control device (not shown) and sent to the centering device 113. The upper piezo actuator 117 then performs a stroke of 150° with an actuator length of 45 mm against the alignment ring 115, thereby aligning the die 111 with respect to the centering axis 119 and the pre-product guide 107. A better-centered, coated strand is then extruded from the extrusion device 101. The determination of the centricity by the measuring device is repeated continuously during production.

[0073] Thus, a method for sheathing the strand is provided which realizes a radially and longitudinally uniform sheathing of the strand and thereby guarantees its functionality.

Claims

1. Extrusion system (101) for coating wires, cable pre-products or stranded conductors, wherein the extrusion system has an extrusion head (103) with a pre-product guide (107) and a mould die (111), wherein the pre-product guide (107) and the mould die (111) are arranged in relation to one another in such a way that an opening of the pre-product guide (107) allows a moulding compound to be moulded by the mould die (111)into an extruded moulding, and the pre-product guide (107) and / or the mould die (111) are assigned a motorised adjusting device (113), characterised in that the motorised adjusting device (113) has a piezoelectric actuator (117) and the piezoelectric actuator (117) is arranged on the pre-product guide and / or on the mould die (111), such that, if an adjusting signal is applied to the motorised adjusting device (113) by means of a direct linear movement of the piezoelectric actuator (117), the pre-product guide (107) and the mould die (111) can be aligned in relation to one another.

2. Extrusion system (101) according to claim 1, characterised in that the extrusion system (101) has a receiving device for receiving a continuous pre-material, in particular a wire, cable pre-product or a stranded conductor, such that the pre-material can be coated with the moulding compound.

3. Extrusion system (101) according to any one of the preceding claims, characterised in that the motorised adjusting device (101) has a second piezoelectric actuator, a third piezoelectric actuator, a fourth piezoelectric actuator and / or further piezoelectric actuators (117).

4. Extrusion system (101) according to any one of the preceding claims, characterised in that the piezoelectric actuator(s) (117) has / have a travel range of 0.01 nm to 1 mm, preferably 0.1 nm to 200 µm.

5. Extrusion system (101) according to any one of the preceding claims, characterised in that the extrusion system (101) is assigned a measuring device for determining at least one measured variable of an extruded moulded part and / or a control and / or regulating device, such that the adjusting signal can be applied to the motorised actuator as a function of the determined measured variable.

6. Extruder for coating wires, cable pre-products or stranded conductors, characterised in that the extruder has an extrusion system (101) according to any one of claims 1 to 5.

7. Method for coating wires, cable pre-products or stranded conductors using an extrusion system (101) according to claim 5 and / or an extruder according to claim 6, characterised by the following steps: - introducing a continuous wire, cable pre-product or a continuous stranded conductor into the extrusion head, - extruding the moulding compound through the pre-product guide (107) and the mould die (111) to obtain a coated wire, cable pre-product or a coated stranded conductor, - determining at least one measured variable of the coated wire, cable pre-product or the coated stranded conductor using the measuring device, - using the determined measurement variable to generate the adjusting signal, - regulating and / or controlling the motorised adjusting device (113) by applying the adjusting signal, - direct linear movement of the piezoelectric actuator (117) against the pre-product guide (107) and / or the mould die (111), - aligning the pre-product guide (107) and / or the mould die (111) with respect to each other, and - outputting a centred coated wire, cable pre-product or a centred coated stranded conductor.