Method for suctioning fibers from a pulp using a suction device and a suction device

Abstract

A method for suctioning fibers from a pulp using a suction device with a suction tool, and a suction device for suctioning fibers from a pulp with a suction tool that has a plurality of cavities for suctioning fibers are described.

Claims

1. A method for suctioning fibers from a pulp using a suction device with a suction tool that has a plurality of cavities, wherein the cavities have surfaces with openings, the openings being connected to a common suction line via channels, wherein a suction power is changed during a suction process.

2. The method according to claim 1, wherein a negative pressure is generated in the cavities for suction, and the negative pressure for suction has at least two different states.

3. The method according to claim 1, wherein the suction power is changed continuously or in stages.

4. The method according to claim 1, wherein the change in suction power is changed automatically or manually.

5. The method according to claim 1, wherein the change in the suction power is controlled in accordance with at least one of the following parameters: a geometry of the cavities, a position of the cavities in the suction tool, a suction duration, a pulp composition, pulp properties and/or pulp temperature, a weight of fibers already sucked, and a clogging of the cavities.

6. The method according to claim 5, wherein at least one of the parameters is monitored and, when limit values are reached, a change in the suction power is initiated via a control device.

7. A suction device for the suction of fibers from a pulp with a suction tool that has a plurality of cavities for suctioning fibers, wherein the cavities have surfaces with openings that are connected via channels to a common suction line, the suction device having a control device via which a suction power is configured to be varied during a suction process.

8. The suction device according to claim 7, wherein the control device has at least one valve, the at least one valve being operable to change a cross-section of the common suction line in order to change the suction power.

9. The suction device according to claim 7, further comprising at least one sensor unit for monitoring at least a suction pressure in the channels and/or the common suction line, a suction duration, a pulp composition, pulp properties and/or pulp temperature, a weight of fibers already sucked, a clogging of the cavities, wherein the at least one sensor unit is connected to the control device, the control device being configured to carry out a change in the suction power in accordance with a feedback output by the at least one sensor unit.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0025] In the drawings:

[0026] FIG. 1 depicts a schematic representation of a fiber processing device, according to some embodiments.

[0027] FIG. 2 depicts a schematic representation of a suction process with a suction device, according to some embodiments.

[0028] FIG. 3 depicts a schematic representation of the arrangement of cavities, according to some embodiments.

DETAILED DESCRIPTION

[0029] Various embodiments of the technical teaching described herein are shown below with reference to the figures. Identical reference signs are used in the figure description for identical components, parts and processes. Components, parts and processes that are not essential to the technical teachings disclosed herein or that are obvious to a person skilled in the art are not explicitly reproduced. Features specified in the singular also include the plural unless explicitly stated otherwise. This applies in particular to statements such as a or one.

[0030] FIG. 1 shows a schematic representation of a fiber processing device 1000 for producing three-dimensional molded parts from a fiber-containing material, according to some embodiments. In the illustrated embodiment, the fiber-containing material for the production of molded parts is processed in a pulp tank 200 of the fiber processing device 1000. For this purpose, water and fibrous materials as well as additives, if any, can be introduced into a pulp tank 200 via a liquid supply, and the pulp can be prepared in the pulp tank 200 by mixing the individual components with heat input and by auxiliary means, such as an agitator.

[0031] Pulp refers to an aqueous solution containing fibers, where the fiber content of the aqueous solution can be in a range of 0.1 to 10 wt. %. In addition, additives such as starch, chemical additives, wax, etc. can be present. The fibers can be, for example, natural fibers, such as cellulose fibers, or fibers from a fiber-containing original material (for example waste paper). A fiber treatment plant offers the possibility of preparing pulp in a large quantity and providing pulp to a plurality of fiber processing devices 1000.

[0032] The fiber processing device 1000 can be used to produce, for example, biodegradable cups 3000, capsules, trays, plates, and other molded and/or packaged parts (e.g., as holder/supporting structures for electronic appliances). Since a fibrous pulp with natural fibers is used as the starting material for the products, the products manufactured in this way can themselves be used as a starting material for the manufacture of such products after their use, or they can be composted, because they can usually be completely decomposed and do not contain any substances that are harmful to the environment.

[0033] The fiber processing device 1000 shown in FIG. 1 has a frame 100 that can be surrounded by a cladding. The supply units 300 of the fiber processing device 1000 include, for example, interfaces for the supply of media (for example, water, pulp, compressed air, gas, etc.) and energy (power supply), a central control unit 310, at least one suction device 320, line systems for the various media, pumps, valves, lines, sensors, measuring devices, a bus system, etc., and interfaces for bidirectional communication via a wired and/or wireless data connection. Instead of a wired data connection, there can also be a data connection via a fiber optic line. The data connection can be, for example, between the control unit 310 and a central controller for a plurality of fiber processing devices 1000, to a fiber preparation plant, to a service point, and/or further devices. It is also possible to control the fiber processing device 1000 via a bidirectional data connection via a mobile device, such as a smartphone, tablet computer, or the like.

[0034] The control unit 310 is in bidirectional communication with an HMI panel 700 via a bus system or a data connection. The HMI (Human Machine Interface) panel 700 has a display that displays operating data and states of the fiber processing device 1000 for selectable components or the entire fiber processing device 1000. The display can be designed as a touch display so that adjustments can be made manually by an operator of the fiber processing device 1000. Additionally or alternatively, further input means, such as a keyboard, a joystick, a keypad, etc. for operator inputs, can be provided on the HMI panel 700. In this way, settings can be changed and the operation of the fiber processing device 1000 can be influenced.

[0035] The fiber processing device 1000 has a robot 500. The robot 500 is designed as a so-called 6-axis robot and is thus able to pick up parts within its radius of action, to rotate them and to move them in all spatial directions. Instead of the robot 500 shown in the figures, other handling devices can also be provided that are designed to pick up and twist or rotate products and move them in the various spatial directions. In addition, such a handling device may also be otherwise configured, in which case the arrangement of the corresponding stations of the fiber processing device 1000 may differ from the illustrated embodiment.

[0036] A suction tool 520 is arranged on the robot 500. In the illustrated embodiment, the suction tool 520 has cavities (e.g., cavities 350, shown in FIG. 2) formed as negatives of the three-dimensional molded parts to be formed, such as of cups 3000, as suction cavities. The cavities can have, for example, a net-like surface on which fibers from the pulp are deposited during the suction. Behind the net-like surfaces, the cavities are connected to a suctioning device via channels in the suction tool 520. The suction device can be realized, for example, by a suction device 320. Pulp can be suctioned in via the suction device when the suction tool 520 is located within the pulp tank 200 in such a way that the cavities are at least partially located in the aqueous fiber solution, the pulp. A vacuum, or a negative pressure, for suctioning fibers, when the suction tool 520 is located in the pulp tank 200 and the pulp, can be provided via the suction device 320. For this purpose, the fiber processing device 1000 has corresponding means at the supply units 300. The suction tool 520 has lines for providing the vacuum/negative pressure from the suction device 320 in the supply units 300 to the suction tool 520 and the openings in the cavities. Valves are arranged in the lines, which can be controlled via the control unit 310 and thus regulate the suction of the fibers. It is also possible for the suction device 320 to perform a blow-out instead of a suction, for which purpose the suction device 320 is switched to another operating mode in accordance with its design.

[0037] In the production of molded parts made of a fiber material, the suction tool 520 is immersed in the pulp and a negative pressure/vacuum is applied to the openings of the cavities so that fibers are suctioned out of the pulp and are deposited for example on the net of the cavities of the suction tool 520.

[0038] Thereafter, the robot 500 lifts the suction tool 520 out of the pulp tank 200 and moves said tool together with the fibers that are adhering to the cavities and still have a relatively high moisture content of, e.g., over 80 wt. % water, to the pre-pressing station 400 of the fiber processing device 1000, where the negative pressure is maintained in the cavities for the transfer. The pre-pressing station 400 has a pre-pressing tool with pre-pressing molds. The pre-pressing molds can be formed, for example, as positive of the molded parts to be manufactured and have a corresponding size with regard to the shape of the molded parts for receiving the fibers adhering in the cavities.

[0039] In the production of molded parts, the suction tool 520 is moved, with the fibers adhering in the cavities, to the pre-pressing station 400 in such a way that the fibers are pressed into the cavities. The fibers are pressed together in the cavities, so that a stronger connection is thereby produced between the fibers. In addition, the moisture content of the preforms formed from the suctioned-in fibers is reduced, so that the preforms formed after the pre-pressing only have a moisture content of, for example, 60 wt. %. To squeeze out water, flexible pre-pressing molds can be used, which are inflated, for example, by means of compressed air (process air), thereby pressing the fibers against the wall of a cavity of a further suction tool part. As a result of the inflation, both water is squeezed out, and the thickness of the sucked-in fiber layer is reduced.

[0040] During pre-pressing, liquid or pulp can be extracted and returned via the suction tool 520 and/or via further openings in pre-pressing molds or pre-pressing tool parts (cavities). The liquid or pulp discharged during suction via the suction tool 520 and/or during pre-pressing in the pre-press station 400 can be returned to the pulp tank 200.

[0041] After pre-pressing in the pre-pressing station 400, the preforms produced in this way are moved to a hot pressing station 600 on the suction tool 520 via the robot 500. For this purpose, the negative pressure is maintained at the suction tool 520 so that the preforms remain in the cavities. The preforms are transferred via the suction tool 520 to a lower tool body that can be moved along the production line out of the hot pressing device 610. If the lower tool body is in its extended position, the suction tool 520 is moved to the lower tool body in such a way that the preforms can be placed on forming devices of the lower tool body. Subsequently, an overpressure is produced via the openings in the suction tool 520 so that the preforms are actively deposited by the cavities, or the suction is ended, so that the preforms remain on the forming devices of the lower tool body due to gravity. By providing overpressure at the openings of the cavities, pre-pressed preforms that rest/adhere in the cavities can be released and dispensed.

[0042] Thereafter, the suction tool 520 is moved away via the robot 500 and the suction tool 520 is dipped into the pulp tank 200 in order to suction further fibers for the production of molded parts from fiber-containing material.

[0043] After the transfer of the preforms, the lower tool body moves into the hot pressing station 600. In the hot pressing station 600, the preforms are pressed into finished molded parts under heat and high pressure, for which purpose an upper tool body is brought onto the lower tool body via a press. The upper tool body has cavities corresponding to the forming devices. After the hot pressing operation, the lower tool body and the upper tool body are moved away relatively from one another and the upper tool body is moved along the fiber processing device 1000 in the manufacturing direction, where after the hot pressing the manufactured molded parts are suctioned in via the upper tool body and thus remain within the cavities. Thus, the manufactured molded parts are brought out of the hot pressing station 600 and deposited via the upper tool body after the deposition on a transport belt of a conveyor device 800. After the deposition, the suction via the upper tool body is ended and the molded parts remain on the transport belt. The upper tool body moves back into the hot pressing station 600 and a further hot pressing operation can be carried out.

[0044] The fiber processing device 1000 further has a conveying device 800 with a transport belt. The manufactured molded parts made of fiber-containing material can be placed on the transport belt after the final molding and the hot pressing in the hot pressing station 600 and discharged from the fiber processing device 1000. In further embodiments, after placing the molded parts on the transport belt of the conveying device 800, further processing can take place, such as filling and/or stacking the products. The stacking can take place, for example, via an additional robot or another device.

[0045] The fiber processing device 1000 from FIG. 1 shows a possible embodiment. A fiber processing device according to the technical teaching described herein can also have only one forming station with a replaceable tool, e.g., a suction tool 520 or a hot press tool, in which fiber-containing material can be processed, it being possible for different tools for producing different three-dimensional molded parts to be received in the at least one forming station. The further stations and devices shown for the fiber processing device 1000 of FIG. 1 are not absolutely necessary for implementing the technical teaching.

[0046] FIG. 2 shows a schematic representation of a suction process with a suction device 320, according to some embodiments. The suction device 320 has a suction tool 340 with a plurality of cavities 350. The arrangement of the cavities 350 in the underside of the suction tool 340 can be as shown schematically in FIG. 3 for various tool designs. In further embodiments, cavities 350 can also be round, oval or polygonal instead of rectangular in cross-section when viewed from the underside of the suction tool 340. In still further embodiments, cavities of suction tools 340 can be arranged in a circle or polygon.

[0047] In the illustrated embodiments, the cavities 350 have a net-like structure on the inner suction surface. Channels extend from the net-like structure within the suction tool 340, which converge in a common suction line for all channels of the cavities 350. A negative pressure is applied via the common suction line to suck fibers when the suction tool 340 is located in the pulp 210 in such a way that the fibers can be sucked over the inner surface of the cavities 350.

[0048] The suction line is connected to a control device 360, which has a throttle valve in the illustrated embodiment. The cross-section of the suction line can be changed via the throttle valve so that in the schematically shown example, two different pressure states P1 and P2 can be set for the suction of fibers from the pulp 210. For suction, a negative pressure is provided via the common suction line and the control device, which can be P1=0.3 to 0.6 bar absolute pressure, for example in an initial state, i.e. at the start of the suction process. After a definable time interval when the outer cavities 350 are relatively heavily clogged, i.e. a relatively large quantity of fibers has already deposited on the cavity surface, the throttle valve is actuated via the control device 360 so that the cross-section of the suction line is changed. This changes the suction pressure, which is then P2 in the illustrated embodiment. The suction negative pressure P2 can be between 0.7 and 0.9 bar absolute pressure, for example. In still further embodiments, the pressure can be changed in stages or continuously, e.g. by changing the free cross-section in the suction line. In addition to a time specification for switching between the pressure states P1 and P2, the suction negative pressure can be set in accordance with the information from at least one sensor unit, which, for example, ascertains the volume or mass flow in the suction line and transmits it to the control device 360. As soon as the volume or mass flow exceeds at least one limit value, the suction pressure can be switched to at least one other pressure level, or the suction negative pressure can be continuously changed.

[0049] In still further embodiments, a change in the suction pressure can additionally or alternatively occur by displacing the suction tool 320 relative to the pulp surface in the pulp tank 200. It is essential for the cavities 350 to lie in a plane and for the suction tool 320 with the cavities 350 to be displaced parallel to the surface so that the resulting changed pressure situation has the same effect on all cavities 350. This also applies to suction in the pulp tank 200 in general, where a suction pressure can only act uniformly if the pressure situation in the cavities 350 is the same (i.e., for example, no inclined immersion of the suction tool 320, etc.).

[0050] The pressure change due to a displacement of the suction tool 320 during the suction process can, for example, be continuous or in stages, where at least two stages can be provided.

[0051] In the illustrated embodiment, the pulp 210 can be present, for example, as an aqueous fiber mixture in concentrations of 0.2-1.5 wt. % of fibers in a pulp basin 200, from which the suction tool 320 sucks the required amount of pulp 210 or fibers, as shown schematically in FIG. 2 by the arrows. The arising suction volume flow is substantially dependent on the shape and arrangement of the cavities 350 of the suction tool 320.

[0052] After the start of the suction process, the outer cavities 350 close first. One reason for this is that more fiber material can be fed over the entire lower surface of the suction tool 320 in the outer region. In the inner cavities 350, the amount of sucked fiber material is smaller, because more cavities 350 are arranged in the immediate vicinity that also suck fiber material. As soon as the outer cavities 350 have sucked a sufficient quantity of fibers, the inner cavities 350 would suddenly suck more fiber material if the initial suction negative pressure is maintained, so that these would ultimately have the most material. Therefore, after a predeterminable period of time or, as indicated above, by measuring parameters, at least one switchover is performed so that the suction negative pressure is reduced. This ensures that the inner cavities 350 do not clog excessively. As a result, uniform clogging of all cavities 350 is achieved.

[0053] FIG. 3 shows the undersides of suction tools 320 with a plurality of cavities 350, according to some embodiments. In the above example, the suction tool 320 has two inner cavities 350 and ten outer cavities 350. The dashed line surrounds the inner cavities 350 and illustrates the two different cavity groups. Two different suction pressures (see P1 and P2) are sufficient with regard to the method described above and switching.

[0054] In the lower example in FIG. 3, the underside of a suction tool 320 is shown, which has three groups I., II., III. of cavities 350. This suction tool 320 can, for example, be switched in stages for each of the groups I, II and III. As explained above, the switchover can take place depending on the time or after exceeding or falling below limit values, which are compared with parameters that are ascertained by at least one sensor unit and transmitted to the control device 360. The control device 360 can change, for example, the opening cross-section of a common suction line via a valve or other device as a result of the transmitted information or by a specification. In the example in FIG. 3, for example, the cavities 350 of group I. are clogged first. For this purpose, the initial suction negative pressure is changed after an initial time interval. Subsequently, the clogging of group II. of the cavities 350 increases so that after a second time interval, the changed suction negative pressure is changed again, where finally the cavities 350 of the third group in the middle of the suction tool 320 clog, and the sucked fiber material the cavities 350 has the final weight or quantity of fibers.

[0055] With the aid of adjusting the suction power (e.g., suction negative pressure) of a suction tool 320 described herein and the design of a suction tool 320, a significant improvement of the suction in a fiber molding process (wet fiber process) can be achieved, where all cavities 350 of a multi-cavity suction tool 320, which has at least one inner and an outer suction cavity 350, have a uniform fiber distribution so that the sucked fiber cakes and finally preforms and final molded parts do not have any significant differences in weight and material. This benefits downstream manufacturing processes in particular, such as for example hot pressing in a hot pressing station 600, because the introduced thermal energy leads to uniform heating of all preforms, since they do not have different weights and therefore different amounts of water.

LIST OF REFERENCE SIGNS

[0056] 100 Frame [0057] 200 Pulp tank [0058] 210 Pulp [0059] 300 Supply units [0060] 310 Control unit [0061] 320 Suction device [0062] 340 Suction tool [0063] 350 Cavity [0064] 360 Control device [0065] 400 Pre-pressing station [0066] 500 Robot [0067] 520 Suction tool [0068] 600 Hot pressing station [0069] 610 Hot pressing device [0070] 700 HMI panel [0071] 800 Conveying device [0072] 810 Camera [0073] 1000 Fiber processing device [0074] 3000 Cup