ELECTRONIC ASSISTANCE FOR CUTTING PROFILE SAMPLES TO LENGTH, WITH THE EXTRUSION AND TEST PARAMETERS BEING ACCURATELY ASSIGNED

Abstract

Various embodiments of the present disclosure are directed to methods and systems for producing plastic profiles. In one example embodiment, a method is disclosed including the steps of plasticizing a starting material in an extruder on an extrusion line, pressing the starting material through an extrusion die, cooling and calibrating the extruded material in a dry calibration and/or a wet calibration, and cutting the extruded material to length to form individual profile rods, cutting to length one or more profile samples can be requested intermittently at any point in time, applying, via a labeling device, on the profile samples characteristic information relating to the current extrusion process, taking into account the transit time of the profile.

Claims

1. Method for producing plastic profiles including the following steps: on an extrusion line, a starting material is plasticized in an extruder, pressing the starting material through an extrusion die, cooling and calibrating the extruded material in a dry calibration and/or a wet calibration, and cutting the extruded material to length to form individual profile rods, cutting to length one or more profile samples can be requested intermittently at any point in time, applying, via a labeling device, on the profile samples characteristic information relating to the current extrusion process, taking into account the transit time of the profile.

2. The method according to claim 1, wherein the characteristic information is applied to the profile samples by printing thereon or in the form of printed labels.

3. The method according to claim 1, wherein the one or more profile samples are produced immediately after a complete profile rod or after another profile sample.

4. The method according to claim 1, wherein the applied characteristic information is executed at least partially in plain text.

5. The method according to claim 1, wherein the applied characteristic information is coded and relates to a separately stored database.

6. The method according to claim 1, wherein latency times, which occur when changing extrusion parameters, are also accounted for with respect to the transit time of the profile.

7. The method according to claim 1, wherein the transit times of the profile also takes into account the type of information to be applied to the profile samples.

8. The method according to claim 1, wherein the applied information includes one or more of the following: material compositions fed to the extruder, temperatures in the extrusion die, or pressures in the calibration tools.

9. A system for producing plastic profiles on an extrusion line, the system comprising: an extruder configured and arranged to plasticize, in which a starting material is pressed through an extrusion die of the extruder, the extrusion die including a dry calibration and/or a wet calibration, a device configured and arranged for cutting individual profile rods and profile samples to length in response to a request from a control device, and a labeling device configured and arranged, in response to a request from a control device on each profile sample characteristic information relating to the current extrusion process applied to the profile sample, taking into account the transit time of the profile.

10. The system according to claim 9, characterized in that the control device for the labeling is integrated in an overall control device for the extrusion line.

11. The system according to claim 9, characterized in that the labeling device is a printer.

12. The system according to claim 9, characterized in that the labeling device is arranged immediately downstream of a caterpillar take-off.

Description

[0040] The present invention will be explained below with reference to an exemplary embodiment which is shown in a schematic drawing. The FIGURE shows, based on an extrusion line, the process for the requesting of one or more profile samples 8 by an operator, and subsequently the automatic cutting and labeling of these profile samples 8.

[0041] The FIGURE shows the basic structure of an extrusion line for producing window profiles. However, the invention is not limited to window profiles, but rather can also be used in the case of extrusion lines for pipes, technical profiles and the like. In the extruder 1, the melt is prepared from the dry blend. The dry blend is fed to the extruder through the hopper 11. The screws convey the plastic material from left to right through the extruder, with energy being supplied via the screws and the heated cylinder 12, here equipped with four cylinder heating zones 13, wherein the melt is intensively mixed and heated to a temperature of around 195° C. In parallel with the heating, the melt is brought to a pressure of approx. 350 bar and is thus pressed through the extrusion die 15. At the degassing opening 14, gaseous components of the formulation (water vapour due to the moisture content of the dry blend, entrained air, and gases given off from the formulation as a result of heating) are extracted. The conveying speed v.sub.Ex in the extrusion direction E depends mainly on the throughput, the screw geometry and the screw speed. The conveying speed V.sub.EX is variable over the length of the extruder, and it is characteristic for each type of extruder. The throughput is approximately proportional to the screw speed. In other words, to ensure a desired throughput, a certain screw speed must be set, as a result of which a characteristic transit speed and residence time of the dry blend or melt in the extruder, from leaving the filling hopper 11 to emerging from the die 15, can be determined.

[0042] Located after the extruder is the calibration table 2, on which a dry calibration 16 and a wet calibration 18 are mounted. After the melt emerges from the extrusion die 15, it enters the dry calibration 16, here consisting of three dry calibrators 17. The melt, which is still hot, corresponds approximately to the profile contour and is sucked against the calibrator wall by negative pressure and is thus cooled externally. For further cooling, the profile 20 passes through some vacuum tanks 18. Located therein, at intervals of 100 mm to 300 mm, are numerous plates which support the profile against the negative pressure in the vacuum tanks. By direct contact of the profile 20 with cooled water, the profile is largely cooled. Wet calibration lengths of up to approx. 18 m are customary, depending on the take-off speed v.sub.Ab, the outer wall thicknesses of the profile and the number of inner walls.

[0043] The caterpillar take-off 4 serves to transport the profile through the calibration. The profile 20, which has already been cooled, is clamped between two caterpillars and conveyed in the extrusion direction at the take-off speed v.sub.Ab, wherein typically take-off forces of around 3 kN to 10 kN occur.

[0044] In the subsequent cutting device 5, here configured as a saw 21, the profile 20 is cut to length to form profile rods 22, which usually have a length of 6 m. During the sawing process, the cutting unit 21 is moved in synchronism with the take-off speed. The profile rods 22 that have been cut to length are pushed onwards by the profile 20 until they reach the deposit table 6, and are displaced transversely in the latter. Profile rods which meet the quality requirements are moved manually or by a mechanical device into profile containers; profiles which do not meet the quality requirements enter a scrap container.

[0045] After emerging from the extrusion die 15, the profile 20 moves at the take-off speed v.sub.Ab through the entire downstream line until it reaches the cutting unit 21. During ongoing profile extrusion, usually even when producing scrap or during the start-up process, profile rods of predefined length are cut. The control device “always knows” the times at which a cutting process is to be activated. This applies also to manually triggered cutting processes and even in the event of changes in the take-off speed and/or the extruder speed.

[0046] In order to be able to reflect as accurately as possible, when analysing the extrusion process, the “history” of a particular profile sample 8 from when the dry blend enters the extruder until the profile sample 8 is cut to length, the characteristic distances or length dimensions of the extruder, of the tool, of the downstream line and of the labeling device must be known in addition to the extrusion parameters (various setting data and measurement data). These data must be input once for the extrusion line and for the tool and are then available for each production batch of the relevant profile.

[0047] To cut one or more profile samples 8 to length, the machine operator first inputs a request signal. Further information is then exchanged in the dialogue with the control device: [0048] number and lengths of the requested profile samples 8, which are to be taken one after the other; [0049] time at which the sample(s) is/are to be taken: [0050] immediately=as soon as the profile sample 8 just printed arrives at the cutting unit; [0051] after the next complete profile rod 22 has been produced; [0052] after the melt currently emerging from the die 15 has passed through; [0053] after the dry blend currently being fed to the extruder 1 has passed through; [0054] after a time delay of x minutes; [0055] etc.; [0056] entering the short comment to be printed.

[0057] As soon as a profile sample 8 has been requested, the control device is ready to determine the extrusion parameters and supplementary parameters to be printed on the profile sample 8 over a short period of time before the printing time, for example to calculate the mean values of the relevant measured values over 15 seconds shortly before printing.

[0058] As soon as this information is known, the control device 7 determines the time at which printing is to take place, taking into account the time offset between the labeling device 3 and the cutting position of the cutting unit 21. In other words, the profile sample 8 is first labeled (or a label is adhered thereto) at the corresponding profile position, so that the label subsequently appears at a short safety distance behind the first cut end face of the profile sample 8. It is advantageous that all the profile samples 8 that are cut immediately after one another have the same label as the one cut first.

[0059] In parallel with the labeling and cutting to length of the profile samples 8, the control device also determines the exact time frame over which the routinely recorded extrusion parameters (all digitally recorded setting parameters and measured values of the entire extrusion line) are to be assigned to the specific profile sample 8. The end point of the appropriate time frame is the time at which printing is to take place. The meaningful start of the time frame is the time at which the dry blend for producing the specific profile sample 8 has been fed to the extruder 1, preferably earlier than said time by a safety period of around 3 to 5 minutes. The duration of the time frame is calculated from the distance between the labeling device and the die 15 divided by the take-off speed plus the transit time through the extruder 1, which is approximately proportional to the screw speed. The duration of the time frame can therefore be defined automatically by the control device based on the known variables. A check of the correctness can occasionally be carried out by means of a colouring test of the dry blend.

[0060] It is advantageous to store and manage all the data that can be assigned to a particular profile sample 8 in a separate database, independent of the database in which all the recorded extrusion parameters are routinely stored. This also applies to the quality tests subsequently carried out on the test samples 8 (for example geometry measurements, mechanical test values, measured colour values, etc.). The “profile sample code” printed as standard on the profile samples 8 is provided for this purpose: All the data that are closely related to a particular profile sample 8 are stored under this code and can be analysed in retrospect with high accuracy. The extrusion parameters have much more significance if they can subsequently still be related to the quality of a retained profile sample 8.