Device and method for cleaning rollers

Abstract

The invention relates to a device for cleaning rollers of a calender (1) by means of which molten polymer compound can be formed into continuous films or sheets. According to the invention, a cleaning system (6) is arranged on the calender (1), wherein the cleaning system (6) comprises a cleaning unit (7) having a cleaning head (8), wherein the cleaning unit (7) can be positioned along the roller, wherein the cleaning head (8) can be moved over the surface of the roller by means of the cleaning unit (7), wherein the cleaning unit (7) is connected to at least one linear guide (10), wherein a cleaning tool (9) is arranged on the cleaning head (8), wherein the cleaning tool (9) is rotatable and the rotation axis (18) of the cleaning tool (9) is oriented perpendicularly to the rotation axis (19) of the roller to be cleaned. The invention also relates to a corresponding method for cleaning the rollers.

Description

[0001] Device and method for cleaning rollers

[0002] Description:

[0003] The invention relates to a device and a method for cleaning rollers of a smoothing machine by means of which molten plastic mass can be formed into continuous films or sheets.

[0004] Thermoforming is a recognized process within plastics processing for the mass production of lids, cups, and trays as packaging. Suitable films are produced on calendering machines. Typically, three-roll calenders are used, in which one or two adjustable roller gaps are created via various mechanical roller adjustment concepts. The plastic, emerging from a slot die, is calibrated in the calender, where the film's surface finish is achieved. The melt exiting the extruder is calibrated and cooled. Sometimes, downstream cooling rollers are used to reach the required final temperature.

[0005] During this process, deposits can accumulate on the smoothing rollers over time. These deposits increase over time and can then affect the final product, leading to rejects. To counteract this, the rollers are cleaned both during production and after production.

[0006] Previously, cleaning was done manually with a cleaning cloth and, if necessary, additional cleaning agent. Following the update of the calender standard, the area around the smoothing rollers and the nozzle must be completely shielded from the operator, preventing them from reaching into this area.

[0007] Such a cooling device is known, for example, from EP 1 600 277 Bl. It discloses a device for calibrating and cooling a plastic film or plastic sheet, which consists of at least two cooling or calibrating rollers, wherein a cooling section is connected downstream of the rollers, and wherein the downstream cooling section consists of pairs of rollers arranged one behind the other.

[0008] A roller cleaning device is known from DE 37 16 902 A1, which discloses a device for the temporary cleaning of a roller on calenders, smoothing machines, and the like. This device is cleaned by means of a rotating cleaning element. This element has a small width compared to the roller length and is mounted in a frame that is movable along a crossbeam parallel to the roller. This allows for particularly reliable cleaning.

[0009] Application_BCG162WO docx BCG 162 WO Oct-25 The purpose of the invention is to provide a device and a method for cleaning the rollers by means of which the individual rollers of the smoothing unit can be cleaned without an operator having to intervene in the danger zone around the smoothing rollers.

[0010] The solution to the problem with regard to the device is characterized in connection with the preamble of claim 1 in that a cleaning system is arranged on the smoothing unit, wherein the cleaning system comprises a cleaning unit with a cleaning head, wherein the cleaning unit is positionable along the roller, wherein the cleaning head is movable over the surface of the roller by means of the cleaning unit, wherein the cleaning unit is connected to at least one linear guide, wherein a cleaning tool is arranged on the cleaning head, wherein the cleaning tool is rotatable and the axis of rotation of the cleaning tool is aligned perpendicular to the axis of rotation of the roller to be cleaned.

[0011] This device makes it possible to clean a roller of the smoothing unit without operator intervention. The roller rotates around its axis, and the cleaning head cleans it.

[0012] This increases the cleaning effect and allows the cleaning tool to be adapted or replaced to suit the circumstances.

[0013] In particular, the rotation axis of the cleaning tool, aligned perpendicular to the roller surface, produces a superior cleaning effect compared to cleaning devices known from the prior art. Streaks or similar markings on the roller surface are wiped away, which is not achieved with cleaning systems that clean with or against the direction of roller rotation.

[0014] Furthermore, the cleaning system is designed to include a spray unit. The cleaning effect can be enhanced by a cleaning agent reservoir, which is also integrated into the system and supplied to the cleaning process via the spray unit.

[0015] In order to position the cleaning head above the roller and press it against the surface, the design provides that the cleaning head is operatively connected to a gas spring and a linear drive, and includes a drive for the cleaning head.

[0016] BCG 162 WO Oct-25 The solution to the problem relating to the method is characterized in conjunction with the preamble of claim 5 in that the rollers of the smoothing machine are cleaned by means of a cleaning system, wherein the cleaning system has a cleaning unit which is positioned over one of the rollers, wherein a cleaning head arranged in the cleaning unit is moved along the roller surface and cleans the roller surface by means of a cleaning tool arranged on the cleaning head, wherein the cleaning tool is rotated about an axis of rotation which is oriented perpendicular to the roller surface.

[0017] As explained above, this method makes it possible to clean a roller of the calender without operator intervention. The roller rotates around its axis, and the cleaning head cleans it.

[0018] For more precise positioning, further training stipulates that the cleaning tool is pressed against the roller surface by means of a gas spring and positioned by means of the linear drive.

[0019] Advantageously, the cleaning tool rotates, which increases the cleaning effect. This effect is further enhanced by adding a cleaning agent from a container via a spray unit. Depending on the design, it is possible to spray the cleaning agent onto either the roller surface or the cleaning tool itself.

[0020] Furthermore, it is planned to equip the cleaning system with a monitoring system which, in conjunction with the calender control, enables roller detection and the position of the cleaning unit, allowing specific rollers to be targeted and cleaned using a cleaning program.

[0021] The drawings schematically show a device according to the invention:

[0022] Fig. 1 schematically shows a typical smoothing machine arrangement.

[0023] Fig. 2 shows a 3D view of a smoothing machine.

[0024] Fig. 3 shows a 3D view of the cleaning system.

[0025] Fig. 4 shows a section through the cleaning unit

[0026] Figure 1 shows a typical smoothing unit arrangement with a slot die 2 through which the plastic mass, melted in an extruder, is fed to the smoothing unit 1 via smoothing rollers 3. Several cooling and calibration rollers 4 follow. The resulting film is marked with position number 5.

[0027] Figure 2 of BCG 162 WO Oct-25 shows a 3D view of a calender 1. The calendering rollers 3 and the downstream cooling and calibrating rollers 4 are also visible. The device according to the invention for cleaning the rollers is represented as a cleaning system 6. The cleaning unit 7 is arranged on the cleaning system 6 and can be moved along the roller in the X-direction by means of the linear guide 10. The cleaning system 6 can also be positioned in the Z-direction over one of the other rollers via a further linear guide (not shown). For this purpose, the design of the feet 17 would have to be modified (marked in Figure 3) so that these modified feet 17 can be mounted on a further linear guide that extends to the left and right outside the rollers in the Z-direction, thus allowing the cleaning system 6 to be positioned over other rollers as well. Appropriate sensors can be installed in the cleaning unit 7 so that this position can also be determined.

[0028] This additional sensor technology can be integrated into the linear drive's position monitoring system. Since the linear drive typically only contains a Hall sensor that detects the extension or retraction distance, it cannot determine the position relative to the roller. This distance must be set in the controller and can then be repeatedly approached. For this control to be proactive, more advanced sensors are required that detect the roller and measure the distance. This also makes it possible to identify which roller the cleaning system 6 is positioned above. For this purpose, additional sensors are installed that are independent of the Hall sensor integrated internally in the linear drive.

[0029] A cleaning head 8 is arranged on the cleaning unit 7, which includes a cleaning tool 9 that is replaceable and can rotate around its own axis. The cleaning agent, which has a different composition depending on the requirements, is stored in the cleaning agent container 11. The cleaning agent is applied to the cleaning tool 9 via the spray unit 12. It is also conceivable to offer an embodiment in which the cleaning agent can be sprayed directly onto the roller surface. The 3D coordinate system is marked with position 13.

[0030] Figure 3 shows a close-up view of the cleaning system 6. The cleaning unit 7 is connected to the linear guide 10, which allows the cleaning unit 7 to be moved in the X-direction. The cleaning head 8 with the cleaning tool 9 is located on the cleaning unit 7. In this embodiment, the cleaning container 11 and the spray unit 12 are fixed to the frame of the cleaning system 6. The axis of rotation of the cleaning tool 8 is designated by position number 18. This axis of rotation 18 is oriented perpendicular to the roller surface; for clarity, the axis of rotation 19 symbolically represents the roller to be cleaned.

[0031] BCG 162 WO Oct-25 is shown. The cleaning device thus rotates around the Y-axis shown in Figure 2 and the roller around the X-axis.

[0032] Figure 4 shows a cross-section through the cleaning unit 7. The cleaning head 8 is located in the lower part of the cleaning unit 7. The cleaning tool 9 is connected to the cleaning head 8 by means of a quick-release fastener 16. The gas spring 14 presses the cleaning tool 9 onto the roller surface. The linear drive 15 positions the cleaning tool 9 above the roller. The linear drive 15 also includes position monitoring, which allows the correct position above the roller to be cleaned to be set and corrected if necessary. In conjunction with the calender control and a cleaning program stored therein, specific rollers in the system can be accessed and cleaned. The axis of rotation of the cleaning tool 9 is also labeled 18. The drive 20 for the cleaning head 8 is installed in the housing.

[0033] BCG 162 WO Oct-25 Reference List:

[0034] 1 Smoothing unit

[0035] 2 wide slot nozzles

[0036] 3 Smoothing roller

[0037] 4 cooling and calibration rollers

[0038] Slide 5

[0039] 6 Cleaning system

[0040] 7 cleaning units

[0041] 8 cleaning heads

[0042] 9 Cleaning tools

[0043] 10 linear guides in the X direction for 6

[0044] 11 cleaning agent containers

[0045] 12 spray units

[0046] 13 3D coordinate grid

[0047] 14 gas springs for 9

[0048] 15 linear actuators for 8

[0049] 16 quick-release fasteners

[0050] 17 feet by 6

[0051] 18 Rotation axis of 9

[0052] 19 Rotation axis of the roller to be cleaned

[0053] 20 drive for 8

[0054] BCG 162 WO Oct-25

Claims

7 Patent claims:

1. Device for cleaning rollers of a smoothing machine (1) by means of which molten plastic mass can be formed into continuous films or sheets, characterized in that a cleaning system (6) is arranged on the smoothing machine (1), wherein the cleaning system (6) comprises a cleaning unit (7) with a cleaning head (8), wherein the cleaning unit (7) is positionable along the roller, wherein the cleaning head (8) is movable over the surface of the roller by means of the cleaning unit (7), wherein the cleaning unit (7) is connected to at least one linear guide (10), wherein a cleaning tool (9) is arranged on the cleaning head (8), wherein the cleaning tool (9) is rotatable and the axis of rotation (18) of the cleaning tool (9) is aligned perpendicular to the axis of rotation (19) of the roller to be cleaned.

2. Device according to claim 1, characterized in that the cleaning system (6) comprises a spray unit (12).

3. Device according to one of the preceding claims, characterized in that the cleaning head (8) is operatively connected to a gas spring (14) and a linear drive (15).

4. Device according to one of the preceding claims, characterized in that the cleaning unit (7) comprises a drive (20) for the cleaning head (8).

5. Method for cleaning rollers of a smoothing machine (1) by means of which molten plastic mass is formed into continuous films or sheets, characterized in that the rollers of the smoothing machine (1) are cleaned by means of a cleaning system (6), wherein the cleaning system (6) has a cleaning unit (7) which is positioned over one of the rollers, wherein a cleaning head (8) arranged in the cleaning unit (7) is moved along the roller surface and cleans the roller surface by means of a cleaning tool (9) arranged on the cleaning head (8), wherein the cleaning tool (9) is rotated about an axis of rotation (18) which is oriented perpendicular to the roller surface.

6. Method according to claim 5, characterized in that the cleaning tool (9) is pressed against the roller surface by means of a gas spring (14) and positioned by means of the linear drive (15). BCG 162 WO Oct-25 7. Method according to claim 5 or 6, characterized in that the cleaning tool (9) rotates, thereby increasing the cleaning effect.

8. Method according to one of claims 5 to 7, characterized in that a cleaning agent is supplied to the cleaning process from a cleaning agent container (11) via a spray unit (12).

9. Method according to one of claims 5 to 8 characterized in that the cleaning system (6) is equipped with a monitoring system by means of which, in conjunction with the calender control, roller detection and the position of the cleaning unit (7) are possible, whereby certain rollers are approached and cleaned by means of a cleaning program. BCG 162 WO Oct-25

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