RETRACTION DEVICE

Abstract

It is provided an extrusion device for a plastic profile, in particular a hollow chamber profile, with an extruder, an extrusion nozzle arranged at the exit of the extruder for forming the plastic profile the plastic profile subsequently being guided through a calibration device, a downstream removal device for the plastic profile, a cutting device for cutting off parts of the extruded plastic profile and a weighing device for measuring the profile weight. A profile monitoring device is provided for detecting at least one profile parameter of the plastic profile in the extrusion direction after it has emerged from the extrusion nozzle and/or a process monitoring device is provided for detecting at least one process parameter in and/or before of the extruder, the extrusion nozzle, the calibration device, the removal device and/or the cutting device.

Claims

1. Retraction device for an extrusion device for a plastic profile, in particular a hollow chamber profile, with an extruder, an extrusion nozzle arranged at the outlet of the extruder for forming the plastic profile and at least one further device, which is arranged downstream of the extruder in an extrusion direction (E), for drawing the plastic profile into the at least one further device, having at least one traction means and a connecting element for connection to the plastic profile, characterised in that a coupling element is arranged on the at least one traction means, via which coupling element the connecting element is detachably connected to the at least one traction means.

2. Retraction device according to claim 1, characterised in that the connecting element is designed as a clamping device for connecting to the plastic profile by clamping the plastic profile and/or clipping to the plastic profile.

3. Retraction device according to claim 1, characterised in that the connecting element is designed to cool the plastic profile.

4. Retraction device according to claim 1, characterized by a winding element on which the at least one traction means can be wound up.

5. Retraction device according to claim 1, characterised in that the at least one traction means is a flexible traction means.

6. Retraction device according to claim 1, characterised in that the at least one traction means is a rigid traction means.

7. Retraction device according to claim 1, characterised in that at least two traction means are provided, a first traction means being a flexible traction means and a second traction means being a rigid traction means.

8. Retraction device according to claim 7, characterized in that the rigid traction means (is arranged on the coupling element and the flexible traction means is arranged on the rigid traction means, so that the rigid traction means is pullable with the flexible traction means through the at least one further device.

9. Retraction device according to claim 1, characterised in that the coupling element is positively and/or non-positively connected to the connecting element.

10. Retraction device according to claim 1, characterised in that the connecting element for connecting to the plastic profile is adjustable between an open position and a closed position, the connecting element being connectable to the coupling element in particular only in the closed position.

11. Retraction device according to claim 1, characterised in that the connecting element fixes the plastic profile by means of a toothing in a form-fitting and/or force-fitting manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Based on exemplary embodiments, the monitoring device and the monitoring system are described with reference to the figures.

[0084] FIG. 1 shows a schematic representation of an extrusion device with a control device.

[0085] FIGS. 2A and 2B show sectional views of a calibration device.

[0086] FIG. 3 shows graphical representation of a symmetrical penalty function.

[0087] FIG. 4 shows graphical representation of an asymmetric penalty function.

[0088] FIG. 5 shows a view of a retraction device.

[0089] FIG. 6 shows a view of a connection element.

[0090] FIG. 7 shows a view of a retracting device which is arranged at a extrusion device.

[0091] FIG. 8 shows a view of a coupling element.

[0092] FIG. 9 shows a view of an embodiment of a slide-in element.

[0093] FIG. 10 shows views of an embodiment of a slide-in element.

[0094] FIG. 11 shows views of an embodiment of a connection element.

[0095] FIG. 12 shows cross-section through a calibration device through which a retractor is pulled.

[0096] FIG. 13 shows a view of an embodiment of a coupling element.

[0097] FIG. 14 shows a schematic representation of a cleaning device with a bottle jet nozzle.

[0098] FIG. 15 shows a component with two cleaning devices.

[0099] FIG. 16 shows a sectional view with two construction elements with four cleaning devices.

DETAILED DESCRIPTION

[0100] FIG. 1 shows the schematic structure of an extrusion device known per se, whereby the extrusion direction E here runs from left to right.

[0101] A homogeneous melt is conveyed from an extruder 1 in an adjustable quantity at the required temperature into the downstream extrusion nozzle 2. In the extruder, e.g. plastic granulate (one or more types of plastic) is melted, whereby the plastic, highly viscous plastic melt is conveyed by extruder screws in the direction of the extrusion nozzle 2.

[0102] The extrusion nozzle 2 shapes the homogeneous plastic melt delivered under pressure into the desired cross-sectional shape, namely a plastic profile, in particular a hollow chamber profile. Temperature control devices can be provided in and/or on the extrusion nozzle, with which, for example, the finished plastic profile can be cooled after it emerges from the extrusion nozzle 2. It is also possible that a temperature control device inside the extrusion nozzle cools and/or heats the forming plastic profile.

[0103] A calibration device 3 takes the still thermoplastically deformable plastic profile 10 coming out of the extrusion nozzle 2 and fixes it to the desired dimensions by cooling.

[0104] The cooling takes place in the calibration device 3 in a wet calibration and/or a dry calibration. In wet calibration, heat energy is dissipated by water which is brought into contact with the plastic profile 10.

[0105] A removal device 4 is connected downstream of the calibration device 3, whereby the plastic profile 10 is typically pulled through a caterpillar take-off.

[0106] Downstream of the removal device 4, a cutting device 5 is arranged in extrusion direction E, in which the continuously produced plastic profile 10 is cut to a predetermined dimension, e.g. with a saw.

[0107] A weighing device 6, which is connected downstream of the cutting device 5, enables each individual profile bar to be weighed during the extrusion process.

[0108] The result should regularly be a plastic profile 10, whose material properties, surface and internal and external dimensional accuracy must meet specified requirements.

[0109] In the following, embodiments for a control or regulation are described that can ensure this.

[0110] A profile monitoring device 20 is used to detect at least one profile parameter of the plastic profile 10 after it has left the extrusion nozzle 2. This means that a property of the plastic profile 10 is detected on the path between the extrusion nozzle 2, the calibration device 3, the removal device 4, the cutting device 5, the weighing device 6 and/or in at least one of the respective devices 3, 4, 5, 6. Sensors that are aligned with the corresponding property of the plastic profile 10 can be used for this purpose, for example.

[0111] In addition to at least one profile parameter, a process monitoring device 21 additionally or alternatively detects at least one process parameter in and/or before the extruder 1, the extrusion nozzle 2, the calibration device 3, the removal device 4, the cutting device 5 and/or the weighing device 6. The recording can also take place in the devices 1, 2, 3, 4, 5, 6 and/or on the path of the plastic profile between the devices 1, 2, 3, 4, 5, 6.

[0112] The profile monitoring device 20 and the process monitoring device 21 are shown separately here, although they can also be integrated on a computer.

[0113] The data from the profile monitoring device 20 and/or the process monitoring device 21 are then used by a control device 30 to set at least one manipulated variable S1, S2, S3, S4, S5, S6 on the extruder 1, on the extrusion nozzle 2, on the calibration device 3, on the removal device 4, on the cutting device 5 and/or on the weighing device 6 as a function of the data.

[0114] Thus, a structure of a multi-variable control is present here, in which the input data are obtained from in the plastic profile 10 and/or from the units 1, 2, 3, 4, 5, 6 of the extrusion device. It is not mandatory that all input and output variables are always linked with each other.

[0115] The control device 30 has a means for converting input data into manipulated variables S1, S2, S3, S4, S5, S6. This means can be, for example, a control law (e.g. a PID controller, a model-based controller) which firmly links an input with an output, i.e. a manipulated variable S1, S2, S3, S4, S5, S6. However, the means can also have a more complex model in which many inputs are linked to many outputs, i.e. manipulated variables S1, S2, S3, S4, S5, S6. Such a model can be given as a calculation model and/or in the form of a self-learning model, e.g. in the context of machine learning.

[0116] In the following, some profile parameters will be dealt with first. For example, an optical sensor (e.g. a camera and image processing) can be used to detect the wall thickness of the plastic profile. The wall thickness can be an outer wall or the wall of a hollow chamber.

[0117] Also with an optical sensor, at least one parameter concerning the surface quality, in particular the colour, the gloss, the streakiness, the roughness and/or the gloss can be determined. This can be done, for example, between the units 1, 2, 3, 4, 5, 6, as the plastic profile 10 is easily accessible here.

[0118] With a sensor, e.g. a camera, at least one parameter of the shape deviation of the plastic profile 10 from a predetermined shape can be detected. E.g. with image processing, in particular a curvature parameter and/or an angle parameter can be determined, which represents the deviation from a standard.

[0119] An infrared transmitter can also be used to determine at least one temperature of the plastic profile 10, whereby for reasons of accessibility, this measurement is also sensibly carried out between units 1, 2, 3, 4, 5, 6.

[0120] In the following, some process parameters are shown that can be used as an alternative or in addition to the profile parameters.

[0121] The speed of the plastic profile 10 is determined by the removal speed of the removal device 4.

[0122] A camera system or other optical sensor can also be used to ensure at least a correct geometrical alignment of the calibration device 3 and/or the removal device 5 to the extrusion nozzle 2. If, for example, the centering of the plastic profile 10 deviates from the standard value, this leads, for example, to bending, twisting and stresses in the material.

[0123] For a correct cooling, in particular in the calibration device 4, for example at least one temperature value and/or one pressure value can be measured in the extruder 4, in the extrusion nozzle 2, in the calibration device 3 and/or in the removal device 4, since a predetermined temperature profile should generally be established along the extrusion profile 10.

[0124] At the removal device 4, for example, the removal force, a slip and/or the removal speed can be measured, as these parameters have an influence on the entire plastic profile 10.

[0125] Parameters that can be recorded on the cutting device 5 are the lengths and/or the mass of the cut plastic profiles 10.

[0126] The weight of the cutting profile bars can be determined at the weighing device 6.

[0127] Thus, the embodiment has a range of parameters that can serve as input variables for the control device 30. It should be noted that, of course, not all of the input variables have to be measured simultaneously in every case. Subsets of the profile parameters and/or the process parameters can be used.

[0128] In the control device 30, these input values can then be used to determine manipulated variables S1, S2, S3, S4, S5, S6. Again, it is not mandatory that all possible manipulated variables S1, S2, S3, S4, S5, S6 are used.

[0129] In the following, some manipulated variables are described in more detail. One manipulated variable on extruder 1 is the mixture setting of the plastic fed to extruder 1. This manipulated variable S1 can be used, for example, to compensate for deviations in the plastic quality and/or colour. The temperature and/or the speed of the extrusion screws in the extruder also have an influence on the type of plastic profile 10 to be formed.

[0130] For the extrusion nozzle 2, for example, at least one temperature can be a useful manipulated variable S2. This does not necessarily mean an averaged temperature over the extrusion nozzle 2 or the cross-section of the plastic profile 10. Rather, parts of the plastic profile 10 can be specifically influenced with suitable temperature control devices on and/or in the extrusion nozzle 2. The temperature in the extrusion nozzle 2 has an influence on the viscosity of the plastic and thus on the flow speed.

[0131] In the calibration device there are a number of manipulated variables S3 that have an influence on a thermal behaviour. For example, the temperature and/or the water flow can be controlled at one or more points. The use of pressure as manipulated variable S3 has an influence on the shape of the plastic profile 10. However, it is also possible to adjust geometrical parameters with manipulated variables S3, for example, by the at least one manipulated variable S3 at the calibration device 3 being an automatic positioning change of at least one calibration nozzle with respect to the extrusion nozzle 2. This makes it possible to compensate for alignment errors between the calibration device 3 and the extrusion nozzle 2.

[0132] On the removal device 4, the at least one manipulated variable S4 can influence the removal speed and/or the contact pressure.

[0133] In the embodiment example shown in FIG. 2A and FIG. 2B, the calibration device 3 is set up to enable detection of the degree of filling of the walls of plastic profiles, in particular solid profiles. On the calibration device 3, in operation, a gap is formed between an inner surface of a passage 30 of the calibration device 3, through which the plastic profile 10 passes, and the plastic profile 10. The calibration device 3 is further adapted to direct a gaseous medium into the gap. The gaseous medium is directed into the gap through a passage 31 from a source 32 for the gaseous medium, such as an air nozzle.

[0134] The passage 31 can be arranged in a front section of the dry calibration device in the direction of extrusion, as shown in FIG. 2A, or in a rear section of the dry calibration device in the direction of extrusion, as shown in FIG. 2B. In principle, the passage 31 can also be arranged in a middle section of the calibration device 3. The gaseous medium can also be fed into the passage through a plurality of passages.

[0135] The gaseous medium is extracted through vacuum channels and/or escapes from the dry calibration, for example, through a front intake. The dynamic pressure of the gaseous medium depends on the size of the gap. If the gap narrows, the dynamic pressure in the medium increases. This means that the wall of the plastic profile is thicker. The degree of filling is therefore greater. The dynamic pressure is determined by measuring the pressure in the supply line at a constant volume flow of the gaseous medium.

[0136] A probability of the plastic profile getting stuck on the dry calibration depends on the size of the gap. With a small gap, the probability of getting stuck is greater than with a large gap. The degree of filling is recorded via the profile monitoring device, if necessary, using the dynamic pressure. The control device uses the data and is arranged to do one or more of the following: (i) triggering an alarm, (ii) adjusting a manipulated variable S4 on the removal device 4 as a function of the degree of filling, for example making the removal device 4 take off the plastic profile faster or slower or making the calibration device 3 move backwards in the extrusion direction.

[0137] By detecting the degree of filling, the risk of the plastic profile getting stuck between the extrusion nozzle and the dry calibration is reduced. This can reduce the production of rejects, i.e. plastic profiles with undesired profile parameters. It also reduces the risk of having to interrupt production for maintenance of the extrusion device.

[0138] FIG. 3 shows a representation of a penalty function as a function p_s(x)=1/(1+e{circumflex over ()}((ax)*sh*((ax)+pn))+1/(1+e{circumflex over ()}((xb)*sh*((xb)+pn)). The function is symmetrical. The parameters a and b indicate the limits of a desired interval for at least one manipulated variable, at least one process parameter or at least one profile parameter. The parameter sh stands for a sharpness of a constraint, described by the penalty function, in the range of the limits. The parameter pn represents a factor for the significance of the constraint. Mathematically, sh stands for a slope of the function p_s at the boundaries a, b and pn for a height to which p_s rises at the boundaries a, b. In the embodiment example shown, the desired interval is located between the values 5 and 5. A penalty for values x that lie outside the desired interval is at a height pn of 100. The slope sh is 2. Such a penalty function can be used, for example, to specify a desired interval for the vacuum at the calibration device or the crowning of the plastic profile. In particular, such a function may be suitable for prescribing the largest possible allowed interval for the selection of the at least one manipulated variable, the at least one process parameter or the at least one profile parameter, so that the process window is as large as possible. The goal is a minimum profile weight with maximum output, minimum rejects and minimum energy consumption.

[0139] FIG. 4 shows another version of a penalty function p_a(x). The function is asymmetric. The parameters a and b indicate the limits of a desired interval of at least one manipulated variable, at least one process parameter or at least one profile parameter. The slope at the limits is different in the present embodiment example. Values of x that lie below the boundary a are thus penalized more heavily (i.e. not used in the optimization or taken into account less) than values that lie above the boundary b. An optimization under such a constraint therefore tends to result in values above the limit a being specified. Such a constraint can be particularly suitable for wall thickness or weight per metre of a plastic profile, since wall thickness and weight per metre must not fall below a certain minimum lower limit, but larger values can be acceptable in principle. Furthermore, the minimum is close to the lower limit so that the function can be used to optimize material consumption.

[0140] FIG. 5 shows a view of a retracting device 7 on a calibration device 3 with a winding element 70 on which a flexible traction means 71 in the form of a rope can be wound. A rigid traction means 72, which is designed as a rod, is arranged on the flexible traction means 71. The rod 72 is arranged on a coupling element 73. The coupling element 73 is connected to a connecting element 74. The connecting element 74 is connected to a plastic profile 10, which is pulled through the calibration device 3 by the retraction device 7.

[0141] FIG. 6 shows a view of a connecting element 74. The connecting element 74 comprises two pincer parts which can be connected to each other in a pincer-like manner, so that a jaw 7410 of the connecting element 74 can be opened by a scissor-like movement of the two pincer parts relative to each other. A toothing 740 is arranged on each pincer part at a connection section 741, which is provided for connection to the plastic profile 10. The connecting element 74 further comprises a coupling section 742, which is provided for connection to the coupling element 73. A projection 7421, 7422 is arranged on the coupling section 742 for each pincer part, wherein the projections of the pincer parts adjoin each other in the closed state of the connecting element 74.

[0142] FIG. 7 shows a view of a retraction device 7 arranged on an extrusion device. The retraction device 7 has been inserted into a calibrating device 3 against an extrusion direction, so that a connecting element 74 of the retraction device 7 protrudes from the calibrating device 3 for connecting a plastic profile 10 to the retraction device 7.

[0143] FIG. 8 shows a view of a coupling element 73. The coupling element 73 has a projection 730 on which the connecting element 74 can be fixed. Furthermore, two recesses 731 are provided on the coupling element 73, in which wings 751 of an insertion element 75 can engage. In principle, at least one recess 731 for the insertion element 75 can be provided on the coupling element 73.

[0144] FIG. 9 shows a view of an embodiment of a slide-in element 75. The slide-in element 75 is used for connection to the coupling element 73 for simply pushing the coupling element 73 through the calibrating device 3 or another device of the extrusion device against the extrusion direction E. The slide-in element 75 is removed from the coupling element 73 before the plastic profile 10 is drawn in. Afterwards, the connecting element 74 is hooked in. The slide-in element 75 has an engagement 750 in which the projection 730 of the connecting element 74 can be inserted. Furthermore, the slide-in element 75 has two wings 751 which are provided to engage in recesses 731 on the connecting element 74, so that the connecting element 74 and the slide-in element 75 are positively connected in a direction opposite to the extrusion direction.

[0145] FIG. 10 shows further views of an embodiment of the slide-in element 75.

[0146] FIG. 11 shows views of an embodiment of a connecting element 74 and an extruded plastic profile 10 to which the connecting element 74 can be connected.

[0147] FIG. 12 shows a cross-section through a calibration device 3 through which a retracting device is pulled. 7

[0148] FIG. 13 shows a view of an embodiment of a coupling element 73. A rigid traction means 72 is arranged on the coupling element 73;

[0149] FIG. 14 shows a schematic representation of a cleaning device 80 with a flat jet nozzle 81. This can be used, for example, to generate a jet of a cleaning agent in a defined width and direction which, in particular, does not impair the still soft surface of the plastic profile 3. Such a cleaning device 80 can be part of a system with which a cleaning agent can be introduced into or connected to the calibration device 3 (see FIG. 16) in order to remove it from soft deposits that accumulate over timedepending on the material composition of the extruded plastic profile 10on the steel surface inside the calibration device 3.

[0150] The cleaning device 80 is not only supplied with cleaning agent, but also with signals from the control device 30. In this way, in particular, a temporal and/or quantitative control of the jet can take place, whereby the cleaning agent can comprise a liquid, a gas or a mixture of both. One possibility of control is that the cleaning agent is applied at intervals. If the cleaning agent is applied as a thin film, it can be drawn into the gap between the calibration device and the plastic profiles and cause cleaning there.

[0151] FIG. 15 shows a component 82, which can be connected to a calibration device 3 not shown here, with two cleaning devices 80, whereby the upper cleaning device 80 emits the cleaning agent upwards, the lower cleaning device 80 emits to the right. The cleaning device 80 is designed here with a flat jet nozzle 81, although in principle other nozzle shapes, e.g. with a circular cross-section, can also be used.

[0152] The jets of cleaning agent are shown in more detail in FIG. 16, where two construction elements 82 are provided with a schematically shown calibration device 3 with a total of four cleaning devices 80, which again also have flat jet nozzles. The components 82 are arranged on both sides of the flow channel for the plastic profile 10.

[0153] In the embodiment shown here, the cleaning agent is applied specifically to single-walled profile sections, whereby the contours in the flow channel are shown accordingly in FIG. 16. The single-walled profile sections can also protrude slightly from the plastic profile 10. In this case, the cleaning agent can be drawn into the gap between the plastic profile 10 and the calibration device 3 (indicated here by a rectangular area) as part of a drag flow.

[0154] In the case of the cleaning device 80 at the top right in FIG. 16, the supply line of the cleaning agent is shown, which is emitted upwards here. For the three other cleaning devices 80, the directions of emission are only graphically indicated.

[0155] In principle, more or less cleaning devices 80 can also be used

LIST OF REFERENCE SIGNS

[0156] 1 Extruder [0157] 2 Extrusion nozzle [0158] 3 Calibration device [0159] 30 Gap [0160] 4 Removal device [0161] 5 Cutting device [0162] 6 Weighing device [0163] 10 Plastic profile [0164] 20 Profile monitoring device [0165] 21 Process monitoring device [0166] 30 Control device [0167] 7 Retracting device [0168] 70 Winding element [0169] 71 flexible traction means [0170] 72 rigid traction means [0171] 73 Coupling element [0172] 730 Projection [0173] 731 Recess [0174] 74 Connection element [0175] 740 Interlocking [0176] 741 Connection section [0177] 7410 Mouth [0178] 7411 Clamping jaw [0179] 7412 Clamping jaw [0180] 742 Coupling section [0181] 7421 Projection [0182] 7422 Projection [0183] 75 Slide-in element [0184] 750 Engagement [0185] 751 Wing [0186] 80 Cleaning device [0187] 81 Flat jet nozzle [0188] 82 Component [0189] a, b Limit [0190] sh Sharpness [0191] pn Height [0192] E Extrusion direction