Method And Device For Stripping A Material Residue From A Metering Nozzle

Abstract

The invention relates to a method for stripping a material residue from a metering nozzle, wherein the metering nozzle with the material residue is guided past a stripping element such that the material residue comes into contact with the stripping element and is stripped from the metering nozzle, characterized in that the stripping element performs a closed rotational movement by means of which a segment of the stripping element first of all reaches a stripping position, in which the material residue is stripped from the metering nozzle and at least some of the material residue remains adhering on the segment, is then guided with the material residue adhering thereon to a separating position, in which a separating unit is used to separate the material residue from the segment of the stripping element, and is guided back to the stripping position to receive a further material residue. Furthermore, the invention also relates to a device for stripping the material residue.

Claims

1. A method for stripping a material residue from a metering nozzle, the metering nozzle with the material residue being guided past a stripping element, such that the material residue comes into contact with the stripping element and is stripped from the metering nozzle, characterized in that the stripping element performs a closed rotational movement by means of which a segment of the stripping element first reaches a stripping position in which the material residue is stripped from the metering nozzle and at least some of the material residue remains adhering on the segment, is then guided with the material residue adhering thereon to a separating position, in which a separating unit is used to separate the material residue from the segment of the stripping element, and is guided back to the stripping position to receive a further material residue.

2. The method according to claim 1, characterized in that a sealing or adhesive material is metered by means of the metering nozzle.

3. The method according to claim 2, characterized in that a period of time for a rotational movement of the segment from the stripping position to the separating position is greater than the tack-free time of the sealing or adhesive material.

4. The method according to claim 1, characterized in that the rotational movement is clocked.

5. The method according to claim 1, characterized in that the rotational movement is a rotary movement about an axis of rotation.

6. The method according to claim 1, characterized in that the rotating stripping element is driven by a pneumatic pivot drive.

7. The method according to claim 1, characterized in that the stripping element is at least partially coated with an anti-adhesion material or produced from an anti-adhesion material.

8. The method according to claim 1, characterized in that the separating device has at least one scraping blade which rests against the rotating stripping element such that the material residue applied to the segment is pressed against the scraping blade by the rotational movement of the stripping element.

9. The method according to claim 8, characterized in that the material residue is deposited on the segment substantially in the form of an elongate thread (2a to 2g), the thread (2a to 2g) being successively guided to the scraping blade in the separating position.

10. The method according to claim 10, characterized in that the material residue is subjected to water, steam and/or heat downstream of the stripping position and upstream of the separating position.

11. A device for stripping a material residue from a metering nozzle, comprising a stripping disc which is rotatably mounted about an axis of rotation and is used to receive the material residue stripped from the metering nozzle, and a separating unit having at least one scraping blade which rests against the stripping disc, wherein the received material residue can be separated by the scraping blade when the stripping disc rotates.

12. The device according to claim 11, characterized in that the scraping blade is U-shaped and has two blade legs and a blade base, the two blade legs resting against a front main surface and against a rear main surface of the stripping disc, respectively, and the blade base resting against a lateral surface of the stripping disc.

13. The device according to claim 12, characterized in that the blade legs extend from the blade base radially in the direction of the axis of rotation of the stripping disc.

14. The device according to claim 13, characterized in that a main extension of the blade legs and a radial connecting line between the axis of rotation and the blade base enclose an angle.

15. The device according to claim 11, characterized in that the scraping blade is L-shaped and has two blade legs, wherein one blade leg rests against a front main surface and the other blade leg rests against a lateral surface of the stripping disc.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The invention is explained in more detail with reference to the embodiments shown in the drawings. In the drawings:

[0031] FIG. 1 shows a device for stripping a material residue in a first embodiment;

[0032] FIG. 2 shows the embodiment from FIG. 1 from the side;

[0033] FIG. 3 shows a second embodiment of the invention;

[0034] FIG. 4 shows the embodiment from FIG. 3 from the side; and

[0035] FIG. 5 shows a separating unit along the line V-V in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0036] FIGS. 1 and 2 show a device 1 for stripping a material residue 2 from a metering nozzle 3. The device 1 comprises a stripping element 10 and a separating unit 30. The stripping element 10 is designed in the form of a circular stripping disc 11 which is rotatably mounted about an axis of rotation 12.

[0037] The stripping disc 11 has a front main surface 13 and a rear main surface 14, although the rear main surface 14 can only be seen in FIG. 2. A lateral surface 15 extends between the front main surface 13 and the rear main surface 14. A diameter of the stripping disc can be in a range of 50 to 200 mm, preferably between 100 and 150 mm. A thickness of the stripping disc 11 can be in a range of 2 to 25 mm, preferably 3 to 7 mm. The front main surface 13, the rear main surface 14 and/or the lateral surface 15 can be coated with an anti-adhesion material. Alternatively, the stripping disc 11 can be entirely made of the anti-adhesion material.

[0038] The metering nozzle 3, through which a flowable material such as liquid adhesive can be applied to a substrate or also to a component (not shown), is located above the stripping disc 11. After an adhesive bead has been applied to the component, a material residue in the faun of a thread 2a to 2g can remain on the metering nozzle 3, which material residue has to be removed from the metering nozzle 3 before a further adhesive bead is applied. For this purpose, the metering nozzle 3 is guided past the stripping disc 11. The arrow 4 in FIG. 1 and the arrow 5 in FIG. 2 indicate the direction in which the metering nozzle is guided above and past the stripping disc 11. In the illustration in FIG. 2, the metering nozzle 3 is guided above the stripping disc 11 along the arrow 5 from the left to the right. In the illustration in FIG. 1, movement of the metering nozzle 3 extends perpendicularly to and into the drawing plane. A material residue 2 hanging on the metering nozzle 3 is stripped from said nozzle by the movement of the metering nozzle 3 and comes to rest on the front main surface 13. FIGS. 1 and 2 show a state in which the thread denoted by 2g has just been stripped from the metering nozzle 3. It is clear from FIG. 2 that the metering nozzle 3 has just passed a front edge 20 between the front main surface 13 and the lateral surface 15.

[0039] The stripping disc 11 can be divided into a plurality of segments, only two of which segments are indicated by dash-dotted lines in FIG. 1. A first segment is denoted by 16 and is located in a stripping position. A second segment is denoted by 17 and is located in a separating position.

[0040] The segment 16 in the stripping position is used to scrape the material residue to be separated from the metering nozzle 3 from the metering nozzle and receive said residue accordingly when the metering nozzle 3 is passed directly above the segment 16. After the stripping process has been completed, the stripping disc 11 is further rotated in the direction of the arrow 18 until a further segment, not occupied by a material residue, reaches the stripping position (in the case of a face of a clock, the stripping position is located at 12 o'clock).

[0041] The second segment 17 is located in the separating position in which the thread 2a located there is scraped from the front main surface 13 by the separating unit 30. FIG. 1 indicates that an inner part of the thread 2a, seen in the radial direction, has already been separated from the main surface 13 and hangs loosely downward. If the stripping disc 11 is rotated further in direction 18, a middle part and an outer part of the thread 2a will also abut the separating unit 30, so that the thread 2a is finally completely separated from the main surface 13 of the stripping disc 11 and falls downward in the direction of the arrow 19 due to gravity. A collecting container (not shown), into which the separated thread 2a falls, is located below the segment 17 in the separating position.

[0042] FIG. 1 shows further threads 2b to 2f which have already been deposited on the stripping disc 11 by prior stripping processes. Between the individual stripping processes, the stripping disc 11 was rotated further by a certain angle of rotation. Viewed in the circumferential direction, the distance between adjacent threads on the stripping disc 11 can be significantly smaller than shown in FIG. 1. The shown threads 2a to 2g are therefore only exemplary of a plurality of threads which are applied to the front main surface 13 by the metering nozzle 3 being repeatedly passed above the stripping disc 11 and the intermediate further rotation of the stripping disc 11. For example, the distance between two adjacent threads seen in the circumferential direction may be only 2 to 5°. Accordingly, the segments of the stripping disc 11 may also only extend over this circumferential range of 2 to 5°.

[0043] Viewed in direction of rotation 18, no threads are located behind the separating unit 30 (see region between 9 and 12 o'clock). Thus, starting from the state shown in FIG. 1, free segments can be brought into the stripping position by a further rotation of the stripping disc 11, in order to receive further material residues 2 in said segments. As a result of the separating unit 30, the stripping disc 11 can perform one full rotation after the other, which makes continuous use of the device 1 possible. Since the stripping disc 30 is automatically freed from the threads 2a to 2g during normal operation of the device 1, set-up times for cleaning the device 1 or for replacing individual components of the device 1 can be significantly reduced.

[0044] In the embodiment shown here, the separating position is offset by approximately 270° with respect to the stripping position. This means that the stripping disc 11, in correspondingly small steps or also continuously, would have to be rotated by a total of 270° in order for the segment 16 to reach the separating position starting from the stripping position.

[0045] In FIG. 2, for the sake of clarity, only the thread 2g just stripped from the metering nozzle 3 and the lowermost thread 2c, which has been stripped some time before thread 2g, are shown. The stripping disc 11 is rotationally driven by a drive unit 50 which comprises a motor in the form of a pneumatic pivot drive 51, a freewheel 52, and a drive shaft 53. The pneumatic pivot drive 51 performs a first rotary movement in the direction of the direction of rotation 18 and a second rotary movement counter to the first rotary movement. The freewheel 52 is designed such that the second rotary movement of the pivot drive 51 is not transmitted to the drive shaft 53. The drive shaft 53 and the stripping disc 11 connected thereto for conjoint rotation are thus stationary when the pivot drive 51 moves counter to the direction of rotation 18. A transmission (not shown here), which can be provided between the pivot drive 51 and the drive shaft 53, preferably has a transmission ratio, such that the ratio of the angle of rotation of the pivot drive 51 to the angle of rotation of the stripping disc 11 is greater than 1.

[0046] It can also be seen in FIG. 2 that the separating unit 30 rests not only against the front main surface 13 but also against the rear main surface 14. As a result, material residues or parts of material residues that become attached to the rear main surface 14 during the stripping process can also be separated by the separating unit 30.

[0047] In order to change the stripping process such that the material residues 2 as far as possible do not reach the rear main surface 14, the axis of rotation 12 extending horizontally in FIG. 2 can be slightly inclined with respect to the horizontal such that the front main surface 13 is pivoted slightly upward. The rear main surface 14 is in this case rotated slightly downward. Due to this inclined axis of rotation, a rear edge 21 is also offset slightly downward with respect to the front edge 20, as a result of which the distance of the rear edge from the metering nozzle 3 is increased.

[0048] FIGS. 3 and 4 show a further embodiment of the device 1 according to the invention, in which components and features which are similar or identical to the components and features of FIGS. 1 and 2 are provided with the same reference signs. In the description of FIGS. 3 and 4, substantially only the differences from the first embodiment of FIGS. 1 and 2 are described. With regard to the common features, reference is made to the previous description of the drawings.

[0049] The device 1 according to the embodiment of FIGS. 3 and 4 comprises a dip tank 70 into which a lower part of the stripping disc 11 projects. The dip tank 70 is filled with a liquid 71, preferably with water. Each thread 2a to 2g that has been stripped from the metering nozzle 3 and deposited on the front main surface 13 thus passes through the dip tank 70 filled with the liquid 71.

[0050] If the material which is metered through the metering nozzle 3 is a single-component adhesive which hardens by means of humidity or water (steam), the font 70 accelerates the hardening of the threads 2a to 2g on the stripping disc 11. As a result, it is possible to prevent the separating unit 30 from becoming clogged with tacky material over a long period of time and no longer functioning reliably, due to insufficiently hardened threads which still have a tacky surface.

[0051] When using a two-component adhesive, the liquid 71 in the dip tank can have an increased temperature in order to apply heat to the threads. The heat can accelerate the reaction between the two components of the adhesive. Here too, the dip tank is used to accelerate the hardening of the threads on the path from the stripping position to the separating position. Alternatively or additionally, the stripping disc 11 can also be heated directly.

[0052] Regardless of the influence on the hardening, the dip tank 70 can also be used to wet the stripping disc 11 with the liquid 71 in order to reduce the adhesion of the individual threads to the stripping disc 11. However, this does not primarily relate to the already deposited threads which pass through the dip tank, but rather to the future threads, which, during continuous operation of the device 1, reach the then wetted surface of the stripping disc 11 after the stripping disc 11 has passed through the dip tank 70.

[0053] In comparison with the embodiment in FIGS. 1 and 2, the position and orientation of the separating unit 30 are slightly changed in the embodiment in FIGS. 3 and 4. FIG. 5 is a section along the line V-V in FIG. 4. The separating unit 30 has a U-shaped scraping blade 31 having a front blade leg 32, a rear blade leg 33 and a blade base 34. The front ring leg 33 rests against the front main surface 13 of the stripping disc 11 and is used to scrape the threads 2a to 2g, which adhere to the front main surface 13. The rear main surface 14 is freed from any adhering material residues by the rear blade leg 33. The blade base 34 is used to clean the lateral surface 15.

[0054] The front blade leg 32 and the rear blade leg 33 can be of equal length or, as shown here, can also have different lengths. In the embodiment shown here, the front blade leg is longer than the rear blade leg 32 and projects slightly beyond the center point or the axis of rotation 12 of the stripping disc 11. This ensures that the entire front main surface 13 is freed from the threads 2a to 2g.

[0055] It can be seen in FIG. 3 that at least the front blade leg 32 and preferably also the rear blade leg 33 enclose an angle 36, which can be 2 to 20°, with respect to a radial connecting line 35 which connects the blade base 34 to the axis of rotation 12. This ensures that a thread 2a to 2g that extends substantially in the radial direction on the stripping disc 11 abuts the front blade leg 32 successively. As a result, undesired force peaks can be prevented during the separation or scraping of the threads 2a to 2g.

[0056] A free end 37 of the rear blade leg 33 can be used to free an end 54 of the drive shaft 53 facing the stripping disc 11 (see FIG. 4) from any residual materials.