DEVICE AND METHOD FOR COOLING FOIL MATERIAL

Abstract

A device and method for cooling foil material are provided, comprising: a movable belt, wherein the belt is intended for receiving the foil material at a first predetermined position of the device, for transporting the foil material received, and for discharging the foil material at a second predetermined position, wherein the device is adapted to cool the foil material received and/or the belt.

Claims

1. A device for cooling stretch foil material, comprising: a movable belt, wherein the belt is intended for receiving the foil material at a first predetermined position of the device, for transporting the received foil material, and for discharging the foil material at a second predetermined position, a first roll and a second roll, wherein the belt is led over the first roll and over the second roll, wherein the device is adapted to cool the received foil material (100) and/or the belt, a cooling liquid bath, wherein the belt and the foil material are movable through the cooling liquid bath, wherein the first predetermined position being located in an area, where the belt rests on the first roll and the roll is immersed into the cooling liquid bath together with the belt in rotation direction, and wherein the second predetermined position being located in an area where the belt rests on the second roll, and means for blowing water off from the belt the means for blowing water off from the belt being the first means located in the direction of movement of the belt at or behind the second roll.

2. The device of claim 1, wherein the belt is an endless belt, in particular, a belt made from steel, preferably, chromium-plated.

3. (canceled)

4. (canceled)

5. (canceled)

6. The device of claim 1, wherein the first predetermined position is located above the liquid level of the cooling liquid bath.

7. (canceled)

8. The device of claim 1, further comprising: at least one third roll, wherein the at least one third roll is arranged so as to guide the foil material and/or the belt.

9. The device of claim 1, wherein the second roll and/or the at least one third roll are modifiable with respect to their respective position.

10. The device of claim 1, further comprising: a tension means for the foil.

11. The device of claim 10, wherein the second roll and/or the at least one third roll has a smaller diameter than the first roll.

12. The device of claim 1, further comprising: means for separating the foil material from the belt at the second predetermined position.

13. (canceled)

14. (canceled)

15. The device of claim 1, wherein at least one of the rolls comprises a cooling means inside the roll for cooling the belt.

16. The device of claim 1, further comprising: a cooling means for cooling the belt in an area between the second predetermined position and the first predetermined position.

17. The device of claim 1, further comprising: a lay-on system for the melt, in particular, an air knife or an elect-static pinning system.

18. The device of claim 1, further comprising: a cleaning device for removing adhesions from the belt.

19. (canceled)

20. The device of claim 1, further comprising: means for measuring temperatures of the belt at predetermined positions and/or of at least one of the rolls and/or the cooling means and for influencing the cooling efficiency of the cooling means depending on the temperatures measured.

21. The device of claim 20, further comprising a monitoring means for monitoring at least one of drying, contamination, temperature, of the foil material.

22. The device of claim 1, further comprising: an extrusion device for melting the foil material and for applying the molten foil material to the belt.

23. A method for cooling stretch foil material, wherein the foil material is received by a movable belt at a first predetermined position, is transported, and is discharged from the belt at a second predetermined position, and wherein the foil material received and/or the belt is/are cooled, wherein the belt is led over a first roll and over a second roll, wherein the belt and the foil material are moved through a cooling liquid bath, wherein the first predetermined position being located in an area, where the belt rests on the first roll and the roll is immersed into the cooling liquid bath together with the belt in rotation direction, and wherein the second predetermined position being located in an area where the belt rests on the second roll, and wherein water is blown off from the belt by a means for blowing water off, the means for blowing water off being the first means in the direction of movement of the belt at or behind the second roll.

24. The method of claim 23, wherein the belt is an endless belt, in particular, a belt made from steel, in particular, chromium-plated.

25. (canceled)

26. (canceled)

27. (canceled)

28. The method of claim 23, wherein the first predetermined position is located above the liquid level of the cooling liquid bath.

29. The method of claim 23, wherein the foil material and/or the belt is/are guided over at least one third roll.

30. The method of claim 23, wherein the foil material is separated from the belt by means of the at least one third roll and a further roll.

31. The method of claim 23, wherein the belt is kept under tension, in particular, by one of the rolls.

32. The method of claim 23, wherein the foil material is kept under tension by at the least one third roll.

33. The method of claim 32, wherein the second roll and/or the at least one third roll are modifiable with respect to their respective position.

34. The method of claim 33, wherein the second roll has a smaller diameter than the first roll.

35. The method of claim 23, wherein at least one of the rolls is cooled by a cooling means provided inside the roll, and the belt is cooled by the at least one cooled roll.

36. The method of claim 23, wherein at least the side of the foil material facing away from the belt is cooled by means of a cooling means in the area between the second predetermined position and the first predetermined position.

37. The method of claim 23, wherein the foil material is put on the belt by means of a lay-on system, in particular, by means of an air knife or an electro-static pinning system.

38. The method of claim 23, wherein the belt is cleared from adhesions by means of a cleaning means.

39. The method of claim 23, wherein the belt is dried, cleared from water, and/or cleaned in the area between the second predetermined position and the first predetermined position.

40. The method of claim 23, wherein temperatures of the belt are measured at predetermined positions and/or at least at one of the rolls and/or the cooling means, and the cooling efficiency of the cooling means is influenced depending on the temperatures measured.

41. The method of claim 23, wherein the foil material is monitored with respect to drying, contamination, temperature.

42. The method of claim 23, wherein the foil material is melted by means of an extrusion device, and is applied to the belt, in particular, by means of a flat nozzle.

43. A method for producing foil material, wherein the method of claim 23 is used.

Description

[0073] The invention and embodiments thereof are described by means of the drawing in further detail, in which

[0074] FIG. 1 shows a conventional cooling device by means of a cooling roll (chill roll) and water bath;

[0075] FIG. 2 shows temperature paths over time for a known cooling device for a foil production plant 20 m, 525 m/min, a total stretching ratio 50 with an output at the winder of 5.000 kg/h;

[0076] FIG. 3 a first embodiment of the invention;

[0077] FIG. 4 a second embodiment of the invention;

[0078] FIG. 5 output tables for a conventional cooling plant (table a)) and possible output tables for a cooling device according to the invention (table b)); and

[0079] FIG. 6 an exemplary temperature curve for a cooling device according to the invention for a foil production plant 20 m, 650 m/min, a total stretching ratio 50 with an output at the winder of 10.000 kg/h.

[0080] With respect to the first embodiment of the invention according to FIG. 3, the device for cooling foil material 100 comprises a movable belt 10, wherein the belt is intended for receiving foil material 100 at a first predetermined position 21 of the device, for transport of the received foil material 100, and for discharging the foil material 100 at a second predetermined position 31, and a cooling means 40, 50, which is intended for cooling the belt 10 and/or the received foil material 100. The belt 10 is an endless belt made from steel and preferably, is chromium-plated. The belt is directed over a first roll 20 and a second control 30. The rolls 20, 30 serve for deflection and driving of the belt 10.

[0081] The first predetermined position 21 in the direction of movement of the belt is located in front of the entrance of the belt 10 into the cooling means 40, 50, and is located in an area, in which the belt 10 rests on the first roll 20.

[0082] The cooling means, here, comprises a cooling liquid bath 40, 50. The cooling liquid bath comprises a container 40 with a cooling medium 50, here, water. At least one of the rolls 20, 30, in this embodiment both rolls 20, 30, are arranged at least partially within the cooling liquid bath 40, 50.

[0083] The first predetermined position 21, namely, that position at which the foil material 100 is applied onto the belt 10, is located in the area of the first roll 20 above the water level of the cooling liquid bath 40, 50. The first roll 20 is that one of the two rolls 20, 30, which in the direction of movement of the belt is closer to the position at which the belt is immersed into the cooling liquid bath 40, 50. Thereby, it is ensured that the foil material is immersed into the water bath immediately after it has been applied, and thereby, is cooled uniformly and homogeneously from both sides.

[0084] For the application of the foil material 100 out of the melt, e.g., an extrusion device 200 is provided. The molten granulate arrives, via melt lines, at a flat nozzle, through which the melt then is applied through the nozzle slot onto the belt 10.

[0085] An air knife 90 serves for the foil material 100, as soon as it hits the belt 10, being cooled there fast and is applied uniformly over the width of the belt 10 at the surface of the belt. If the application of the foil material 100 is achieved by means of air knives, then this entails a cooling effect for the foil material 100 on the side facing away from the belt.

[0086] The belt 10 with the foil material 100 applied thereon is passed through the cooling liquid bath 40, 50. Thereby, the foil material 100 is cooled further.

[0087] The foil material 100 is separated from the belt 10 at the second predetermined position 31. The second predetermined position 31of coursein the direction of movement of the belt is located downstream of the first predetermined position 21. The second predetermined position 31, in this embodiment, is located in an area, where the belt 10 rests on the second roll 30.

[0088] After separation, the foil material 100 is guided via further rolls 110, 120 and is passed over to a subsequent means for renewed heating and stretching, cutting, and/or for winding.

[0089] Further, a means may be provided, which keeps the belt 10 under tension. This means may be integrated into either one of the rolls 20, 30. The tension means is advantageous, if the distance of the two rolls 20, 30 is modifiable and it has to be ensured that the belt, at constant belt length, nevertheless is stretched for every distance set and does not slip.

[0090] Slipping of the belt may be prevented by the configuration of the surface of the rolls and the side of the belt facing the rolls.

[0091] According to a modification of the first embodiment, the diameter of the second roll 30 may be smaller than the diameter of the first roll 20. Then, the foil material 100 may be released from the belt 10 and already at a very early stage and thus, after a very short distance in the water bath, and may be guided outside of the water bath 40, 50. The second roll 30, here, preferably is arranged completely outside of the cooling liquid bath 40, 50.

[0092] FIG. 4 shows a second embodiment of the invention. According to this embodiment, the belt is still led over a third roll 130, which is arranged in the water bath 40, 50 between the two rolls 20, 30. At this roll 130, the foil material 100 is detached from the belt 10, and is then guided over a fourth roll 140, which also is located within the water bath, out of the water bath to the rolls 110 and 120.

[0093] The rolls 130, 140 may be displaceable vertically and horizontally such that the length, over which the foil material is led within the water bath and thereby, the cooling efficiency, may be varied individually according to the requirements. The rolls 130, 140 may have a smaller diameter than at least the first roll 20.

[0094] The third roll 130 (possibly together with further rolls 140) thus enables a detachment of the foil material from the belt at an arbitrary position and a flexible adjustment of the distance over a further deflection roll, by means of which the foil material remains in the water bath.

[0095] Also here, a means may be provided, which keeps the belt 10 under tension. For this, the third roll 130 may be configured as tension mechanism for the belt 10.

[0096] The tension device also is advantageous for releasing the belt 10 when being replaced. The roll 20 is to be kept stable and fixed during ongoing operation, it may only be driven into a controlled replacement position during a replacement of the belt. The roll 30 and the third roll 130, moreover, ensure the tension equalization of the system during the ongoing operation, e.g., during changes of foil thicknesses. Otherwise, all embodiments of the device, which are described above with reference to the first embodiment or with respect to the modified first embodiment, may be transferred individually or in combination to this second embodiment.

[0097] Also applicable for all embodiments:

[0098] Preferably, the foil material 100 (the melt) hits the belt 10 at a particularly stable position of the belt 10, namely, at a location, where the band 10 rests on the first roll 20.

[0099] The length of the cooling liquid bath 40, 50 may be configured differently according to the cooling requirements. The cooling requirements depend, amongst others, on the desired throughput of the plant and the requirements to the properties and quality criteria determined by the cooling efficiency. Because the belt, for example, with foil material or without foreign material is passed between the rolls 20, 30 freely within the water bath 40, 50, basically, cooling paths of any arbitrary length may be realized. Thereby, also a belt with foil material running very fast still may be cooled sufficiently. Otherwise, the belt may be cleared again on the return path (without foil material) from water, and may also be cooled as well as monitored, and the temperature may be measured. For this, the belt may be directed, if needed, over further rolls at corresponding means.

[0100] The water bath may also be much longer, respectively according to the design of the plant, compared to the belt plant only. Thus, for example, thicker foils may be guided through the water bath longer than thinner foils. By the water circuit and the controlled supply of the cold water, the cooling of the foil and the belt may be further optimized and controlled.

[0101] Because the belt 10 and the foil material 100 move through the water bath, the belt and the foil material can be cooled from both sides, ensuring a more uniform cooling of the foil material in cross-section, but also enabling a faster cooling of the foil material.

[0102] In contrast to a CR, the circumference of the rolls 20, 30, here, is not decisive for the cooling efficiency of the plant. The path, on which the foil material is cooled, primarily is not determined by the circumference of the roll, but rather, amongst others, by the length of the area, in which the belt runs within the water, or is cooled by other cooling means.

[0103] In all embodiments, one or more of the following functional groups may be present:

[0104] Means 70 for cleaning the belt from dirt. The cleaning may be carried out, e.g., by means of (cooling-)water, brushes, (cold) air, or a combination thereof.

[0105] Means 80 for the removal of water (by means of blowing) from the belt. The blowing off of water from the belt is the first means (in the direction of movement of the belt) at or behind the roll 30. The blowing off of water preferably results by means of cold air. The ambient temperature, here, is relatively high, due to the extruder, the melt lines, and the nozzle.

[0106] Means 60 for additional cooling of the belt; if necessary, the belt return path (namely, the area between the second predetermined position 31 and the first predetermined position 21 in the direction of movement of the belt) may also be used in order to cool the belt additionally. Thereby, all cooling methods being technically possible may be employed.

[0107] Means 75 for monitoring the belt with respect to damages and/or residues. These means are located in the area of the belt between the second predetermined position 31 and the first predetermined position 21, and operate on the belt or monitor the belt outside of the water bath, virtually on the return path to that position, where the foil material 100 is applied.

[0108] Means 95 for measuring the temperature of the belt, the foil material, and the water bath may also be present. Measuring means may be provided, which measure the exact temperature of the belt immediately before the new melt is supplied, and thereby allow for an accurate control of the entire cooling process, starting from the roll temperature up to the water temperature and all cooling means.

[0109] Subsequently, an optical automatic cleaning control may take place, which interacts with the cleaning intensity.

[0110] Preferably, the space being respectively necessary may be provided by the corresponding length of the belt.

[0111] Referring to the drive of the belt 10, this may be carried out uniformly and correspondingly controllably with the optimal belt velocity respectively. For the present invention, the drive, because two rolls 20, 30 are available for this, may result from both by means of electronically controlled direct drives, or via either one of the two rolls.

[0112] As long as it is ensured that the belt runs absolutely uniform, it is advantageous to only drive one of the rolls 20, 30, in particular, the second roll 30, which may also be of a smaller dimension, as described above, than the first roll 20, and the axis of which or also the entire roll may also be located outside of the water.

[0113] Concerning the design of the rolls 20, 30, one or both may be closed laterally, and may be cooled internally. For this, one or both rolls 20, 30 may respectively comprise a cooling means 25, 35 provided in the interior of the roll, for cooling the belt.

[0114] Alternatively, one or both rolls 20, 30 may be open completely or partially such that they operate like an open water wheel in the water bath. The supply of cold water may be controlled correspondingly.

[0115] The first roll 20 may have its axis located within the water bath and may, as long as it is not operated as an open water wheel, be supplied with a cooling medium for cooling from the inside. By distributing the functions described above on both rolls 20, 30, namely, cooling by the first roll 20, drive by the second roll 30, the complexity of the individual rolls is reduced.

[0116] Summarizing the above, a particular advantage is that a long and flat cooling liquid bath is enabled, which is realized by the small roll diameter during use of the belt. Thereby, compared to a high and short water bath of a conventional CR, there are better possibilities to control the water amount and temperature, and also a larger amount and surface, which can be cleaned more easily. Also, the foil material may be cleaned more easily from dirt, which it picks up from the water bath. The water may be controlled better with respect to its temperature by targeted supply of cooling liquid to the locations, where it actually is needed. The long water bath is easily accessible (e.g., for the threading of the foil), and it has a larger water surface, where contaminations may flow in and then may be skimmed off such that they cannot reach the belt or the foil again. This is a substantial problem with respect to the CR, it practically picks up all contaminations. Also for this reason, the foil remains on the CR as long as possible, namely, the contaminations remain on the foil, and do not reach the CR. Nevertheless, at the edges, however, they do accumulate.

[0117] Moreover, higher foil output efficiency may be achieved by the cooling device according to the invention. At first, FIG. 5 shows table a) for a known plant with cooling by means of a chill roll. Here, with the fastest machine 525 m/min for BOPP at maximum cooling efficiency referred to foil at the winder (after edge cutting) of 5,000 kg/h is achieved. Table b) of FIG. 5 is applicable for a plant with belt cooling according to the invention, designed for a maximum cooling efficiency of 10,000 kg/h and a rate of 650 m/min with otherwise equal conditions. Thus, a higher foil output can be achieved by the cooling device according to the invention, as far as plant components which are placed upstream and downstream allow this.

[0118] FIG. 6 shows a temperature curve of the cooling device according to the invention for a foil production plant 20 m, 650 m/min, a total stretching ratio 50 with an output at the winder of 10000 kg/h. As can be seen, the temperature curves decrease for the film core (the film interior), the side facing away from the belt, as well as the side facing the belt virtually equally steep, and already meet each other at a higher temperature, here in the example, at about 60 degrees. With respect to the known CR plant (FIG. 2), the three temperature curves run substantially differently, and meet each other only with a far stronger cooling down to about 30 degrees.

[0119] With respect to a further embodiment of the invention, the cooling liquid bath is omitted. Here, the foil material is cooled by the belt 10. For this, the belt 10 itself may be cooled at least by one of the rolls 20, 30. The roll 20 and/or the roll 30 may then be cooled from the roll interior side, namely, may comprise an internal cooling means 25, 35. This embodiment is particularly suitable for foil material made from polyester (e.g., PET) and all foil materials, for which the use of a water bath for cooling is not possible, which are brought from a hot melt onto the belt. Here, the cooling of the foil material 100 results from the belt 10, i.e., from the side of the foil material 100 facing the belt. The cooling efficiency of the belt 10, here, in particular, is determined by the temperature of the belt 10 during supply of the melt, the cooling of the belt by the cooled deflection roll(s), and the length of the area, in which the foil material 100 rests on the belt 10 and is transported by the belt 10. The advantages from the length of the belt, its easier cooling, cleaning, monitoring and measuring are applicable correspondingly.

[0120] A third roll 130 or further rolls, here, are advantageous in order to improve the contact of the foil material 100 to the belt 10, and thereby, improve the cooling.

[0121] With respect to this embodiment, an electro-static pinning means for rapid and uniform supply of the foil material over the width of the belt 10 is provided.

[0122] Otherwise, the embodiments described above and the advantages (e.g., cooling, cleaning, measurement) are applicable correspondingly for this embodiment.

[0123] The device according to the invention may be divided into a drive side and an operation side for all embodiments and variants described. The drive side comprises drives, motors, lines, and the operation side can be opened for cleaning and maintenance work.