Product forming unit for dry manufacturing rigid cellulose products and a method for controlling such product forming unit

Abstract

The present invention relates to a method and a product forming unit for dry manufacturing rigid cellulose products (2) having essentially non-flat general shape from a cellulose blank The product forming unit comprising a moulding tool having a first mould part (15) and a second mould part (16), wherein at least one of the first mould part (15) and the second mould part (16) is displaceable in the axial direction in relation to the other in order to press the cellulose blank therebetween into final shape by applying a predetermined pressure P in the axial direction of the moulding tool, wherein the first mould part (15) comprises a bottom surface (21) and the second mould part (16) comprises a bottom surface (19) and wherein the axial distance between the bottom surface (21) of the first mould part (15) and the bottom surface (19) of the second mould part (16) during the pressing of the cellulose product (2) is T millimetres. The product forming unit further comprises an out-feed device (25) having a movable arm (26) and a first suction device (27) connected to said arm (26), the first suction device (27) of the out-feed device (25) being insertable into the moulding tool between the first mould part (15) and the second mould part (16) after the pressing of the cellulose product (2), wherein the first suction device (27) is displaceable towards the bottom surface (21) of the first mould part (15) in order to engage the cellulose product (2) and has a stop position located X millimetres from the bottom surface (21) of the first mould part (15), wherein X > T and X ≤ 3T.

Description

[0001] PRODUCT FORMING UNIT FOR DRY MANUFACTURING RIGID CELLULOSE PRODUCTS AND A METHOD FOR CONTROLLING SUCH PRODUCT FORMING UNIT

[0002] Technical field of the Invention

[0003] The present invention relates in general to the field of method and apparatus for dry manufacturing of rigid cellulose products having non-flat general shape from cellulose blank. Such cellulose products may be used for packaging, storing, transporting and / or displaying other products such as electronics, tools, jewelry, food, dairy products, cosmetics, etc., and / or may be used as single / multiple use disposable articles. The method and product forming unit are especially defined to secure reliable removal of the rigid cellulose product from the moulding tool. By cellulose products means products that mainly consists of the cellulose part of organic matter.

[0004] The present invention relates specifically to a product forming unit for dry manufacturing rigid cellulose products, the product forming unit comprising a moulding tool having a first mould part and a second mould part, wherein at least one of the first mould part and the second mould part is displaceable in the axial direction in relation to the other in order to press the cellulose blank therebetween into final shape by applying a predetermined pressure P in the axial direction of the moulding tool, wherein the first mould part comprises a bottom surface and the second mould part comprises a bottom surface and wherein the axial distance between the bottom surface of the first mould part and the bottom surface of the second mould part during the pressing of the cellulose product is T millimetres. The present invention also relates specifically to a method for controlling such product forming unit.

[0005] Background of the Invention

[0006] There are many situations where it is desirable to provide two-dimensional (2D) or three- dimensional (3D) shaped objects made of sustainable materials, such as biomaterials, instead of using plastic / polymer materials. A biomaterial commonly used for packaging and disposable articles is wet moulded pulp based on cellulose fibres. Such wet moulded pulp has the advantage of being considered as a sustainable material, since it is produced from biomaterials and can be recycled after use. Wet moulded pulp comprises more or less only water and separated cellulose fibers, and consequently, wet moulded pulp has been popular to use for primary packaging applications (packaging next to the article), for secondary packaging applications (assembly of such primary packages), as well as for manufacturing of disposable articles / products.

[0007] One advantage of using wet-forming techniques is that the moulding tool is usually made of a wire netting / cloth that is filled with a wet cellulose slurry and thereafter the cellulose slurry is dried and obtains the shape of the moulding tool. The final rigid cellulose product is easily removed from the wire netting.

[0008] However, a common disadvantage with all wet-forming techniques is the need for large amounts of water during the preparations of the cellulose pulp and the need for drying during the manufacturing / moulding of the cellulose product, which is a time and energy consuming step leading to low production speed and substantial high investment cost in machines and tooling. Meaning that the wet-forming techniques are not feasible to replace fossil-based alternatives neither in small nor large scale production of rigid cellulose products. Thereto, the aesthetical and mechanical properties of a wet-moulded cellulose product are hard to control with desirable precision, due to un-uniform cellulose pulp and due to the wet moulding manufacturing technique per se.

[0009] Therefore many actors / companies, starting a few decades ago, have changed their focus and investments towards dry-forming techniques wherein rigid cellulose products are manufactured from separated cellulose fibres that are introduced into a product forming unit in the shape of a cellulose blank / web, wherein the cellulose blank is formed / moulded into the shape of the intended cellulose product and wherein the cellulose fibres are bonded to each other using heat and pressure. The dry-forming techniques comprises different steps of generating an air-laid cellulose blank, that is fed into a product forming unit, i.e. thermo-forming press.

[0010] The technical field of dry manufacturing rigid cellulose products having non-flat general shape, such as trays, lids, or the like, i.e. wherein the forming / pressing is performed in one step using a moulding tool having a first / male mould part and a second / female mould part configured to cooperate with each other, is well known. However, the sub-technical field of reliably removing the final rigid cellulose products from the moulding tool, is still exposed to challenges.

[0011] It is known within another technical field of pressing metal sheets into non-flat general shape, to use one or more suction devices / cups to remove the final product from the moulding tool. In such situations, should there be a problem concerning reliable removal of the pressed metal product, one may advantageously lower the under-pressure level of the suction device and mechanically force the suction device harder against the metal sheet. These measures will not provide damage to the pressed metal product. However, such measures would be disastrous should there be a problem concerning reliable removal of pressed cellulose product originating from an air-laid cellulose blank.

[0012] The cellulose blank that is fed / transported into the moulding tool is more or less fluffy, i.e. having a bulk of short / small separated cellulose fibres that are loosely connected to each other in the shape of a blank / web. During the moulding / pressing of the rigid cellulose product having non- flat general shape, the separated cellulose fibres will fill up and be pressed into all tiny recesses in the surfaces of the mould parts. Thus, there is an immediate risk, especially for trays having a large bottom portion, that there will arise a vacuum condition between the pressed cellulose product and the bottom of the mould part when the suction device is lowered into contact with the cellulose product, and this may lead to fully unsatisfied removal or partial tearing of the cellulose product. In such situations the production / manufacturing has to be abruptly stopped and the machine be manually cleaned and checked. If the moulding tool is not empty upon start of the next loading / pressing cycle the moulding tool may become damaged. Trying to lower the under-pressure level of the suction device and mechanically forcing the suction device harder against the surface of the pressed cellulose product will only worsen the vacuum condition underneath the cellulose product and thereto it will leave marks on the surface of the cellulose product. The vacuum condition will become worse since the pressed cellulose product is still a little air permeable and the actual suction device will then counteract introduction of air underneath the cellulose product. For wet moulded cellulose products, a vacuum condition between the mould part and the cellulose product cannot arise thanks to the permeable nature of the wire netting / cloth.

[0013] Thereto, in a situation when no cellulose blank was actually loaded into the moulding tool at the beginning of the present loading / pressing cycle, or if the pressed cellulose product stick to the second / wrong mould part, the suction device during lowering will contact the surface of the warm moulding tool and partly melt and stick to the surface of the first mould part, which will have negative effect on and discolour the next cellulose product to be pressed. Thereto the suction device will attach firmly to the metal surface and risk breaking the out-feed device when the suction device is raised to lift the non-present cellulose product. Thus, the system assumes that it has engaged / grasped the cellulose product and initiate lifting. One legitimate reason for not loading a cellulose blank is that the specific cellulose blank has been rejected / scraped upstream the product forming unit.

[0014] Thus, there is still a need in the art for a reliable, cheap and unharmful dry-forming technique / process for dry manufacturing rigid cellulose products having non-flat general shape, wherein the pressed cellulose products as well as the out-feed device are protected from damage during the step of removal of the cellulose product from the moulding tool.

[0015] Object of the Invention

[0016] The present invention aims at obviating the aforementioned and other disadvantages and failings of previously known methods and devices for dry manufacturing rigid cellulose products, and at providing an improved product forming unit and method for dry manufacturing rigid cellulose products having non-flat general shape, wherein reliable removal of pressed cellulose product originating from an air-laid cellulose blank from the moulding tool is secured.

[0017] A primary object of the present invention is to provide an improved product forming unit and method for dry forming / manufacturing rigid cellulose products having non-flat general shape, wherein the environmental benefits as well as time and energy saving benefits of conventional dry-forming techniques are maintained. It is another object of the present invention to provide an improved product forming unit and method for dry forming / manufacturing rigid cellulose products having non-flat general shape, wherein the pressed cellulose products are protected from damage during the step of removal of the cellulose product from the moulding tool. It is another object of the present invention to provide an improved product forming unit and method for dry forming / manufacturing rigid cellulose products having non-flat general shape, wherein the out-feed device is protected from damage during the step of removal of the cellulose product from the moulding tool. of the Invention

[0018] According to the invention at least the primary object is attained by means of the initially defined product forming unit and method having the features defined in the independent claims. Preferred embodiments of the present invention are further defined in the dependent claims.

[0019] According to a first aspect of the present invention, there is provided a product forming unit of the initially defined type, wherein the product forming unit further comprises an out-feed device having a movable arm and a first suction device connected to said arm, the first suction device of the out-feed device being insertable into the moulding tool between the first mould part and the second mould part after the pressing of the cellulose product, wherein the first suction device is displaceable towards the bottom surface of the first mould part in order to engage the cellulose product and has a stop position located X millimetres from the bottom surface of the first mould part, wherein X > T and X < 3T.

[0020] According to a second aspect of the present invention, there is provided a method for controlling a product forming unit configured for dry manufacturing rigid cellulose products having essentially non-flat general shape from a cellulose blank using a product forming unit as defined herein above, wherein the method comprises the steps of:

[0021] - providing the cellulose blank into the moulding tool between the male mould part and the female mould part,

[0022] - displacing at least one of the male mould part and the female mould part in the axial direction in relation to each other, towards each other,

[0023] - pressing the cellulose blank between the male mould part and the female mould part, wherein the axial distance between the bottom surface of the first mould part and the bottom surface of the second mould part during the pressing of the cellulose product is T millimetres,

[0024] - displacing at least one of the male mould part and the female mould part in the axial direction in relation to each other, away from each other,

[0025] - inserting the first suction device of the out-feed device into the moulding tool between the male mould part and the female mould par,

[0026] - displacing the first suction device towards the bottom surface of the female mould part in order to engage the cellulose product and stopping at a stop position located X millimetres from the bottom surface of the female mould part, wherein X > T and X < 3T, and

[0027] - removing the rigid cellulose product from the moulding tool using the first suction device of the out-feed device.

[0028] Thus, the present invention is based on the insight that it is of uttermost importance to have control of the location and operation of the out-feed device in order to secure reliable engagement and removal of the rigid cellulose product without damaging the pressed cellulose products or the out-feed device during the step of removal of the delicate cellulose product from the moulding tool. Thus, the inventors have realized that not crashing the suction device into contact with the cellulose product but stop above the cellulose product will secure that the delicate cellulose product will be lifted from the mould part to the suction device at minimal risk for vacuum condition between the cellulose product and the mould part, and will secure that the out-feed device is not damaged should the moulding tool contain no cellulose product after the pressing cycle.

[0029] The present invention provides the advantage that contact between the first mould part of the moulding tool, which may be warm, and the suction device is always prevented. The present invention also provides the advantage that the ratio of successful removal of undamaged cellulose products will increase.

[0030] According to various example embodiments of the present invention the out-feed device comprises a second suction device connected to said movable arm, the second suction device of the out-feed device being insertable into the moulding tool between the first mould part and the second mould part after the pressing of the cellulose product in order to engage the cellulose product together with the first suction device. Thereto, the second suction device has a stop position located Y millimetres from the bottom surface of the first mould part, wherein Y > T and Y < 3T. Using a plurality of suction devices improve reliable and robust removal of cellulose products having large bottom portions. Using a plurality of suction devices provides the possibility to have different stop locations for the suction devices and / or different under-pressure activation timing in order to provide minor tilting of the cellulose product and minimize the risk for vacuum condition.

[0031] Further advantages with and features of the invention will be apparent from the following detailed description of preferred embodiments.

[0032] Brief of the

[0033] A more complete understanding of the abovementioned and other features and advantages of the present invention will be apparent from the following detailed description of preferred embodiments in conjunction with the appended drawings, wherein:

[0034] Fig. 1 is a schematic illustration of a production line or apparatus for dry manufacturing rigid cellulose products,

[0035] Fig. 2 is a schematic illustration of a moulding tool, wherein a cellulose blank is provided into the moulding tool between the first / female mould part and the second / male mould part,

[0036] Fig. 3 is a schematic illustration of the moulding tool according to figure 2 during forming / pressing of the cellulose product, Fig. 4 is a schematic illustration of the moulding tool according to figures 2 and 3 after the forming / pressing step and the pressed cellulose product is released from the moulding tool,

[0037] Fig. 5 is a schematic illustration of the pressed cellulose product according to figure 4, wherein the scrap area is removed from the final cellulose product,

[0038] Fig. 6 is a schematic illustration of an inventive out-feed device according to a first embodiment, wherein the out-feed device is inserted into the moulding tool between the first / female mould part and the second / male mould part,

[0039] Fig. 7 is a schematic illustration of the out-feed device according to figure 6, wherein the first suction device is displaced to the stop location,

[0040] Fig. 8 is a schematic illustration of the out-feed device according to figures 6 and 7, wherein the out-feed device together with the cellulose product are removed from the moulding tool,

[0041] Fig. 9 is a schematic illustration of an inventive out-feed device according to a second embodiment, wherein the out-feed device comprises a plurality of suction devices and wherein the out-feed device is inserted into the moulding tool between the first / female mould part and the second / male mould part,

[0042] Fig. 10 is a schematic illustration of the out-feed device according to figure 9, wherein the first suction device and the second suction device are displaced to the respective stop location which are located at the same height, and

[0043] Fig. 11 is a schematic illustration of the out-feed device according to figure 9, wherein the first suction device and the second suction device are displaced to the respective stop location which are located at different heights.

[0044] Detailed description of preferred embodiments of the invention

[0045] As used herein, the term "air / dry moulding / forming or air / dry laying / laid" means a well- known method according to which separated cellulose fibres are formed into a cellulose blank / sheet.

[0046] In air-laying technique, small / short fibres having a normal length in the range of 0,5 to 70 mm, for instance 1 to 10 mm, are separated and captured by an air stream / flow, and then laid on / applied to a forming mesh / surface, usually using a low pressure at the other side of the mesh / surface. The general terms "air / dry laying" and "air / dry moulding" are used interchangeably herein. The cellulose fibre carrying air flow may be generated by suitable device located upstream and / or downstream the forming mesh / surface.

[0047] Reference is initially made to figures 1 and 5, wherein figure 1 disclose a schematic illustration of a generic production line / apparatus for dry manufacturing rigid cellulose products, wherein said apparatus is generally designated 1. The production line 1 is configured for manufacturing rigid cellulose products, generally designated 2, having essentially non-flat general shape from separated cellulose fibres. Such a production line 1 may be arranged and set-up according to different well-known ways. Figure 5 disclose an example of a rigid cellulose product / tray 2. The apparatus 1 may have automatic transfer / handling between the different process steps, and / or may have manual transfer / handling between the different process steps, and thereto the apparatus 1 may have intermediate storing and / or additional process steps between the disclosed process steps, and / or the process steps may be located at different sites.

[0048] Figure 5 disclose an example of a rigid cellulose product 2 in the shape of a tray / container, wherein the tray is formed using the inventive method. The tray 2 comprises a circumferential wall 3 and an opening 4 defined by a circumferential rim / brim 5 connected to the upper / free end of the wall 3. According to figure 5 embodiment the brim 5 has an angled shape having an essentially radially extending upper surface and a turned-down outer edge, however it shall be pointed out that the cross-section of the brim 5 may have other shapes. The tray 2 may have truncated cone shape having straight wall 3, narrowing in the direction away from the opening 4, in accordance with figure 5 embodiment. The tray 2 may for instance have curved-shaped wall 3 seen in the axial plane. By having inclined walls 3 multiple trays 2 are stackable one inside the other when they are empty. The tray could also be a mug / cup, or the like container. The cross section of the circumferential wall 3 in the radial plane may have any suitable shape, circular, oval, rectangular, polygonal, etc., and may differ in shape and / or dimension along the axial extension of the tray 2. The tray 2 comprises a bottom 6, wherein the bottom 6 is entirely flat or the bottom may comprise local ribs, projections, etc., for strength and rigidity of the cellulose product. The bottom 6 may be located at the very lower end of the wall 3, according to figure 5 embodiment, and / or be partly located at an axial distance from the lower end of the wall 3, or a combination thereof. The circumferential wall 3 is connected to and extends in the axial direction upwards from the bottom portion 6.

[0049] Cellulose raw material 7, i.e. comprising mainly the cellulose part of organic matter, is provided to the production line, and is fed to a separating / disintegrating unit 8 in order to obtain individualized / separated cellulose fibres. The separated cellulose fibres are thereafter transported by an air stream / flow to a dispenser of a cellulose blank / sheet forming unit 9. The cellulose fibres are laid by the dispenser on a moving or stationary perforated surface of the cellulose blank forming unit 9. The cellulose fibre carrying air flow may be generated by suitable device located upstream and / or downstream the perforated surface. Thereafter the generated cellulose blank, generally designated 10, is transported / transferred to a product forming unit 11, whereby rigid cellulose products 2 are formed and discharged from the product forming unit 11.

[0050] The cellulose blank forming unit 9 may be configured to generate a continuous cellulose blank / web 10 and / or discontinuous / discrete cellulose blanks 10. Discontinuous / discrete cellulose blanks 10 are fed into the product forming unit 11.

[0051] The cellulose raw material 7 may be in the form of reeled pulp or paper, bale of cellulose pulp, paper, etc. and / or sheets of paper, cellulose pulp, etc. In case said cellulose raw material 7 is in the form of sheets and / or reeled pulp or paper, it can be fed directly into the separating unit 8. However, in case said cellulose raw material 7 is in the form of a bale or compact stacks of sheets, etc. one or more shredders and / or one or more additional separating / disintegrating units 8 may be necessary to be used for separating and dosing said cellulose raw material 7 from said bale or sheets in smaller quantities. The shredder(s) prepare cellulose raw material 7 to be accepted by said separating unit 8. The separating unit 8 disintegrates the cellulose raw material 7 into separated cellulose fibres. Said one or plurality of shredder(s) are arranged before said one or a plurality of separating unit(s) 8, so that an output of one of said shredder is connected to an input of one of said separating units 8. The shredders may be arranged in parallel to each other or in series with each other, and the disintegrating units 8 may be arranged in parallel to each other or in series with each other. The shredders and the disintegrating units 8 together constitute a cellulose fibre separating unit, arranged upstream the cellulose blank forming unit 9.

[0052] Said cellulose raw material 7 may be constituted by virgin cellulose fibres and / or recycled cellulose fibres and may originate from wood pulps such as kraft pulp, sulphite pulp, mechanical pulp, thermomechanical pulp (TMP), chemical treated mechanical pulp, chemi-thermomechanical pulp (CTMP), and / or from non-wood pulps such as bagasse, bamboo, abaca, hemp, flax, cotton.

[0053] The separating unit 8 may according to various embodiments be constituted by a hammer mill. In said separating unit 8 the cellulose raw material is separated into fibres having a normal length in the range of 0,5-70 mm, preferably less than 10 mm. The length of said fibres may be customized by adjusting the internal properties of the separating unit 8 and / or by choosing a different separating unit 8 and / or choosing different cellulose raw material 7. The fibre length for wood pulp is according to various embodiments in the range 0,5-4 mm, preferably in the range 1,7-3, 6 mm. According to various embodiments the fibre length for non-wood pulp is in the range 0,5-70 mm.

[0054] The production line 1 may comprise a pre-compression and / or imprinting unit 12, located downstream the cellulose blank forming unit 9 and upstream the product forming unit 11. In the pre-compression and / or imprinting unit 12, an air-laid fluffy cellulose blank 10 having a first thickness may be compressed into a cellulose blank 10 having a second thickness, wherein said second thickness is thinner than said first thickness, and / or may be provided with an imprinting pattern. During the pre-compression / imprinting the cellulose blank is made more coherent and easier to handle, since the pre-compression / imprinting generates internal bindings between individual cellulose fibres preventing mutual separation of the cellulose fibres.

[0055] The product forming unit 11 comprises a press unit 13, and may optionally comprise a preheating unit 14 arranged upstream the press unit 13. According to various example embodiments said cellulose blank 10 may be heated to an elevated temperature before being fed into the press unit 13 of the product forming unit 11. In such embodiment(s) where the cellulose blank 10 is preheated before being fed into the press unit 13, said press unit 13 may or may not comprise heating. According to various example embodiment said press unit 13 may be a heated press unit 13 for heating said cellulose blank 10 during pressing. In the case of a heated press unit 13, preheating of said cellulose blank 10 using a pre-heating unit 14 is optional. According to various example embodiments preheating of the cellulose blank 10 in said pre-heating unit 14 may be combined with a heated press unit 13. Having a pre-heating unit 14 in combination with a heated press unit 13 will speed up the manufacturing process in the product forming unit 11, and improve the quality / rigidity of the final rigid cellulose product 2. In the product forming unit 11 the cellulose blank 10 is heated to a temperature in the range 120 - 200 °C in order to obtain adequate rigidity and strength in the final cellulose product 2.

[0056] Reference is now made to figures 2-4. The press unit 13 comprises a moulding tool having a first mould part 15 and a second mould part 16 having co-operating designs, wherein at least one of the first mould part 14 and the second mould part 16 is / are displaceable in the axial direction in relation to each other, i.e. reciprocating back and forth in relation to each other, in order to exert pressure to the cellulose blank 10 loaded therebetween. In the figures the mutual displacement is disclosed as being vertical, however the mutual displacement may be horizontal or any other suitable angle. The cellulose blank 10 loaded into the moulding tool, is constituted by the air-laid cellulose blank 10. The air-laid cellulose blank 10 may be generated upstream the product forming unit 11 in the same apparatus / production line and provided / transferred to the product forming unit 11, or may be generated at a separate location and provided / transferred to the product forming unit 11 via intermediate handling and storage.

[0057] According to various embodiments the first mould part 15 of the moulding tool is a female mould part, i.e. having a main recess 17 for receiving a major part of the cellulose blank 10, and the second mould part 16 of the moulding tool is a male mould part, i.e. having a main protrusion 18 for cooperation with said recess 17 of the female mould part by being inserted therein, such that the cellulose blank 10 is pressed into a final rigid non-flat shape by applying a predetermined pressure P in the axial direction of the moulding tool. According to the disclosed embodiment the male mould part 16 is located above the female mould part 15, but according to alternative embodiments the female mould part may be the second mould part and may be located above the male mould part which is then the first mould part. The pressed cellulose product 2 is intended to remain in / on the first mould part 15 after the pressing of the cellulose product 2, irrespective of the angular orientation of the moulding tool.

[0058] The main projection 18 of the male / second mould part 16 has a bottom surface 19, and a wall surface 20 connected to the bottom surface 19 and extending essentially in the axial direction. The main recess 17 of the female / first mould part 15 has a bottom surface 21, and a wall surface 22 connected to the bottom surface 21 and extending essentially in the axial direction. The cellulose blank 10 is pressed between the surfaces of the male / second mould part 16 and the surfaces of the female / first mould part 15 into final shape. The mutual axial distance between the bottom surface 21 of the female / first mould part 15 and the bottom surface 19 of the male / second mould part 16 during the pressing of the cellulose product 2 is T millimetres, wherein T preferably is in the range 0,2-2 millimetres, i.e. equal to the thickness of the bottom 6 of the pressed cellulose product 2. Preferably, T is in the range 0,2-1, 5 millimetres. The mutual distance, taken perpendicular to the surface in question, between the wall surface 20 of the male / second mould part 16 and the wall surface 22 of the female / first mould part 15, is preferably the same as between the bottom surfaces 19, 21. The walls of the moulding tool has to be inclined in order to obtain a release angle for the cellulose product, and in order to obtain adequate press force to the wall region of the cellulose product 2.

[0059] At an outer scrap area 23 of the moulding tool, the mutual distance between the surface of the female mould part 15 and the surface of the male mould part 16 is equal to or more than the mutual distance at the bottom surfaces 19, 21. The part of the cellulose blank 10 located at the scrap area 23 may be left entirely uncompressed in the moulding tool, be partially compressed by applying a predetermined partial pressure less than said predetermined pressure P, or be fully compressed by applying said predetermined pressure P. Thus, radially outside the final rigid cellulose product 2, the cellulose blank 10 comprises a scrap area intended to be cut off. In figure 4 the cellulose product 2 is released and schematically removed from the moulding tool by opening the moulding tool. Figure 5 disclose a schematic illustration of a cellulose tray 2 wherein the scrap 24 is cut off from the cellulose tray 2. The scrap area 17 may be removed in a separate step in the moulding tool, in a subsequent step outside the moulding tool after the pressing of the cellulose product 2, or in a step concurrent with the pressing of the cellulose product 2.

[0060] According to various embodiments. When the compartment of the rigid cellulose tray 2 is filled with objects, a film / cover / lid may be attached to the circumferential rim / brim 5 of the cellulose tray 2, for instance using heat lamination. The lid film may be constituted by a multilayer film comprising polymer, metal, and / or paper.

[0061] According to various embodiments. Before any items are placed in the compartment of the rigid cellulose tray, the rigid cellulose tray 2 may be provided with a liner film adhered to at least to the circumferential rim / brim 5, and preferably also to the wall 3 and / or the bottom 6 of the cellulose tray 2. The liner film may be constituted by a multilayer film comprising polymer and / or metal. The adhesion of the liner film to the tray is preferably heat activated.

[0062] According to various embodiments, the cellulose blank 10 may comprise barrier additives and / or material property enhancing additives, etc., such that the rigid cellulose tray 2 withstand grease, fat, water, vapour, etc. The additives are preferably provided to the cellulose fibers upstream the disintegrating unit 8 or between the disintegrating unit 8 and the product forming unit 11.

[0063] The predetermined pressure P is in the range 40-10000N / cm2, preferably in the range 100- 4000N / cm2. According to various embodiments said predetermined pressures are above 1000 N / cm2, and according to various embodiments said predetermined pressures are below 2500 N / cm2. The holding time during the pressing step is in equal to or more than 1 second and equal to or less than 10 seconds, preferably less than 5 seconds, and most preferably less than 3 seconds. Reference is now especially made to figures 6-8 and 9-11 disclosing a first schematic embodiment of the inventive product forming unit 11 and a second schematic embodiment of the inventive product forming unit 11, respectively. The figures disclose the moulding tool of the press unit 13 and an out-feed device, generally designated 25 and schematically illustrated. The out-feed device 25 is configured to remove the pressed cellulose product 2 from the moulding tool in order to make the moulding tool empty and ready for the loading of the next cellulose blank 10. Thus, part of the out-feed device 25 is insertable into the moulding tool between the male / second mould part 16 and the female / first mould part 15 after the pressing of the cellulose product 2. Thus, the pressed cellulose product 2 is intended to be located in / on the first mould part 15 after the pressing of the cellulose product 2, and after the moulding tool is opened. Thereto, the out-feed device 25 may be arranged to transport the pressed cellulose product 2 to a subsequent step in the apparatus such as trimming of the scrap 24 and / or stacking. According to the invention, the out-feed device 25 makes use of a pneumatic arrangement to grasp and release the cellulose product 2. The out-feed device 25 comprises a movable arm 26 that is mechanically controlled and operated, e.g. a robotic arm.

[0064] Reference is now made to figures 6-8. According to the first embodiment of the product forming unit 11, the out-feed device 25 comprises said movable arm 26 and a first suction device 27 connected to the arm 26. The first suction device 27 is insertable into the moulding tool between the male / second mould part 16 and the female / first mould part 15, and the first suction device 27 is preferably inserted into the moulding tool during the opening of the moulding tool,

[0065] 1.e. when the male mould part 16 and / or the female mould part 15 are traveling away from each other after the pressing of the cellulose product 2. By starting the insertion of the first suction device 27 already before the moulding device is fully open, the pressing cycle time may be decreased, i.e. as long as the different members does not collide. The first suction device 27 is insertable into the moulding tool using the movable arm 26.

[0066] The first suction device 27 is a pneumatic arrangement, that preferably comprises a suction cup 28 configured to engage the cellulose product 2. The suction cup 28 may be made of a resilient material, a rigid material, or a combination thereof, wherein the pressure level in the volume defined by the suction cup 28 is controllable / adjustable. According to various embodiments, at least the lower rim of the suction cup 28 is made of a resilient material in order to obtain better air-tight seal between the suction device 27 and surface of the cellulose product

[0067] 2. According to various embodiments, the pressure level in the volume defined by the suction cup may be above as well as below normal / ambient air pressure.

[0068] A low pressure level entails that the suction device 27 engage / holds the cellulose product 2, and a high pressure level entails that the suction device 27 ejects / drops the cellulose product 2. Alternatively, normal / ambient air pressure is used in order to drop the cellulose product 2. The out-feed device 25 may comprise a high pressure source HP and a low pressure source LP, wherein the first suction device 27 is connected thereto and possibly also to ambient air using an assembly of conduits and controllable valves, in order to alternate therebetween. Alternatively, the out-feed device 25 may comprise only a low pressure source LP, wherein the first suction device 27 is connected thereto and to ambient air using an assembly of conduits and controllable valves, in order to alternate therebetween.

[0069] According to various embodiments, the size of the lower opening of the suction cup 28 is in the range 0,2-20 square centimetres, i.e. corresponding to a diameter of about 0,5-5 centimetres of a suction cup 28 having a circular lower opening. Preferably, the size of the lower opening of the suction cup 28 is in the range 9-16 square centimetres, i.e. corresponding to a diameter of about 3, 5-4, 5 centimetres of a suction cup 28 having a circular lower opening. According to various embodiments, during engagement the low-pressure level is such that the total lifting force from the suction cup(s) 28 is preferably in the range 10-1000 times the weight of the cellulose product 2. Using a higher low-pressure level there is an increased risk that the cellulose product will not be removed from the moulding tool, and using a lower low-pressure level there is an increased risk that the suction cup 28 will leave a mark on the surface of the cellulose product 2 or delaminate the cellulose product.

[0070] According to the invention the first suction device 27 is displaceable towards the bottom surface 21 of the first mould part 15 in order to engage the cellulose product 2 and has a stop position located X millimetres from the bottom surface 21 of the first mould part 15. The stop position distance X millimetres is the smallest distance between the bottom surface 21 of the first mould part 15 and the first suction device 27. It is important that stop position distance X millimetres is greater than the distance T millimetres between the bottom surface 19 of the second mould part 16 and the bottom surface 21 of the first mould part 15 during pressing of the cellulose product 2. Thereby the first suction device 27 will not run into the delicate cellulose product 2, any possible generation of vacuum condition between the cellulose product 2 and the first mould part 15 is minimized, and if there is no cellulose product 2 in / on the first mould part 15 the suction device 27 will not contact the bottom surface 21 of the first mould part. Thereto, the stop position distance X millimetres shall be equal to or less than three times the distance T millimetres between the bottom surface 19 of the second mould part 16 and the bottom surface 21 of the first mould part 15 during pressing of the cellulose product 2. A greater distance will considerably decrease the risk that the first suction device 27 does not engage / grasp the cellulose product 2. Thus, X > T and X < 3T.

[0071] According to various embodiments, the stop position distance X millimetres shall be equal to or less than two times the distance T millimetres between the bottom surface 19 of the second mould part 16 and the bottom surface 21 of the first mould part 15 during pressing of the cellulose product 2. Thus, X > T and X < 2T. This helps to further decrease the risk that the suction device 27 does not engage / grasp the cellulose product 2.

[0072] When the first suction device 27 is located at the stop position, the first suction device 27 is manipulated to engage the cellulose product 2, by decreasing the pressure level in the suction cup 28. Thereby the cellulose product 2 is at least partly lifted from the bottom surface 21 of the first mould part 15. The first suction device 27 may engage the bottom 6 of the cellulose product 2 at the centre thereof or closer to the circumferential wall 3. The activation of the lower pressure in the suction cup 28 may be initiated before the first suction device 27 has reached the stop position, in order to shorten the cycle time, and thereby the intended pressure level has been reached when the first suction device 27 reaches the stop position. The out-feed device 25 and thereby the first suction device 27 is kept still a predetermined waiting time before the out-feed device 25, and the cellulose product 2 are removed from the moulding tool, in order to secure that the cellulose product 2 is connected to the out-feed device 25.

[0073] Reference is now made to figures 9-11. According to various embodiments, the out-feed device 27 further comprises a second suction device 29 that is connected to the movable arm 26, wherein the second suction device 29 is insertable into the moulding tool between the first mould part 15 and the second mould part 16 after the pressing of the cellulose product 2 in order to engage the cellulose product 2 together with the first suction device 27. In order to remove the rigid cellulose product 2 from the moulding tool using the first suction device 27 and the second suction device 29. The second suction device 29 is insertable into the moulding tool using the movable arm 26.

[0074] Thus, the second suction device 29 is displaceable towards the bottom surface 21 of the first mould part 15 in order to engage the cellulose product 2 and has a stop position located Y millimetres from the bottom surface 21 of the first mould part 15. The stop position distance Y millimetres is the smallest distance between the bottom surface 21 of the first mould part 15 and the second suction device 29. It is important that stop position distance Y millimetres is greater than the distance T millimetres between the bottom surface 19 of the second mould part 16 and the bottom surface 21 of the first mould part 15 during pressing of the cellulose product 2. Thereby the suction device 27 will not run into the delicate cellulose product 2, any possible generation of vacuum condition between the cellulose product 2 and the first mould part 15 is minimized, and if there is no cellulose product 2 in / on the first mould part 15 the second suction device 29 will not contact the bottom surface 21 of the first mould part. Thereto, the stop position distance Y millimetres shall be equal to or less than three times the distance T millimetres between the bottom surface 19 of the second mould part 16 and the bottom surface 21 of the first mould part 15 during pressing of the cellulose product 2. A greater distance will considerably decrease the risk that the second suction device 29 does not engage / grasp the cellulose product 2. Thus, Y > T and Y < 3T.

[0075] According to various embodiments, the second suction device 29 is configured as the first suction device 27. The first suction device 27 and the second suction device 29 are distributed over the bottom 6 of the cellulose product 2, i.e. each being closer to the circumferential wall 3 at different / opposite ends of the bottom 6 of the cellulose product 2. According to various embodiments the stop position distance Y millimetres of the second suction device 29 is equal to the stop distance X of the first suction device 27 , i.e. Y = X in accordance with schematic embodiment of figure 10. In such configuration, the lower pressure of one of the first suction device 27 and the second suction device 29 may be initiated before the lower pressure of the other section device is initiated. Thereby, only one end of the cellulose product is lifted from the first mould part 15 in order to prevent vacuum condition between the first mould part 15 and the cellulose product 2 before the entire cellulose product 2 is lifted by activating the other suction device. Alternatively, the lower pressure of the first suction device 27 and the second suction device 29 may be initiated concurrently.

[0076] According to various embodiments the stop position distance Y millimetres of the second suction device 29 is greater than the stop distance X of the first suction device 27, i.e. Y > X in accordance with schematic embodiment of figure 11. In such configuration, when the lower pressure of the first suction device 27 and the second suction device 29 is initiated, one end of the cellulose product is lifted from the first mould part 15 to a greater extent in order to prevent vacuum condition between the first mould part 15 and the cellulose product 2.

[0077] According to various embodiments, with reference to the schematic embodiment of figure 11, the lower pressure of one of the first suction device 27 and the second suction device 29 may be initiated before the lower pressure of the other section device is initiated.

[0078] According to various embodiments, the out-feed device 25 may comprise one or more further suction devices connected to the movable arm 25, in addition to the first suction device 27 and the second suction device 29. Such further suction devices are preferably configured as the first suction device 27.

[0079] Thus, according to the inventive method for dry manufacturing rigid cellulose products 2 having essentially non-flat general shape from a cellulose blank 10 using a product forming unit 11 comprising a moulding tool according to the above, the method comprising the steps of:

[0080] - providing the cellulose blank 10 into the moulding tool between the first mould part 15 and the second mould part 16,

[0081] - displacing at least one of the first mould part 15 and the second mould part 16 in the axial direction in relation to each other, towards each other,

[0082] - pressing the cellulose blank 10 between the first mould part 15 and the second mould part 16, wherein the axial distance between the bottom surface 21 of the first mould part 15 and the bottom surface 19 of the second mould part 16 during the pressing of the cellulose product 2 is T millimetres,

[0083] - displacing at least one of the first mould part 15 and the second mould part 16 in the axial direction in relation to each other, away from each other,

[0084] - inserting the first suction device 27 of the out-feed device 25 into the moulding tool between the first mould part 15 and the second mould part 16, - displacing the first suction device 27 towards the bottom surface 21 of the first mould part 15 in order to engage the cellulose product 2 and stopping at a stop position located X millimetres from the bottom surface 21 of the first mould part 15, wherein X > T and X < 3T, and

[0085] - removing the rigid cellulose product 2 from the moulding tool using the first suction device 27 of the out-feed device 25.

[0086] Feasible modifications of the Invention

[0087] The invention is not limited only to the embodiments described above and shown in the drawings, which primarily have an illustrative and exemplifying purpose. This patent application is intended to cover all adjustments and variants of the preferred embodiments described herein, thus the present invention is defined by the wording of the appended claims and the equivalents thereof. Thus, the equipment may be modified in all kinds of ways within the scope of the appended claims.

[0088] Throughout this specification and the claims which follows, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or steps or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

Claims1. Product forming unit (11) for dry manufacturing rigid cellulose products (2) having essentially non-flat general shape from a cellulose blank (10), the product forming unit (11) comprising a moulding tool having a first mould part (15) and a second mould part (16), wherein at least one of the first mould part (15) and the second mould part (16) is displaceable in the axial direction in relation to the other in order to press the cellulose blank (10) therebetween into final shape by applying a predetermined pressure P in the axial direction of the moulding tool, wherein the first mould part (15) comprises a bottom surface (21) and the second mould part (16) comprises a bottom surface (19) and wherein the axial distance between the bottom surface (21) of the first mould part (15) and the bottom surface (19) of the second mould part (16) during the pressing of the cellulose product (2) is T millimetres, characterized in that the product forming unit (11) further comprises an out-feed device (25) having a movable arm (26) and a first suction device (27) connected to said arm (26), the first suction device (27) of the out-feed device (25) being insertable into the moulding tool between the first mould part (15) and the second mould part (16) after the pressing of the cellulose product (2), wherein the first suction device (27) is displaceable towards the bottom surface (21) of the first mould part (15) in order to engage the cellulose product (2) and has a stop position located X millimetres from the bottom surface (21) of the first mould part (15), wherein X > T and X < 3T.

2. The product forming unit (11) according to claim 1, wherein the stop position of the first suction device (27) is located X millimetres from the bottom surface (21) of the first mould part (15), wherein X < 2T.

3. The product forming unit (11) according to claim 1 or 2, wherein the out-feed device (25) comprises a second suction device (29) connected to said movable arm (26), the second suction device (29) of the out-feed device (25) being insertable into the moulding tool between the first mould part (15) and the second mould part (16) after the pressing of the cellulose product (2) in order to engage the cellulose product (2) together with the first suction device (27).

4. The product forming unit (11) according to claim 3, wherein the second suction device (29) has a stop position located Y millimetres from the bottom surface (21) of the first mould part (15), wherein Y > T and Y < 3T.

5. The product forming unit (11) according to claim 4, wherein the stop position of the second suction device (29) is located Y millimetres from the bottom surface (21) of the first mould part (15), and wherein Y = X.

6. The product forming unit (11) according to claim 4, wherein the stop position of the second suction device (29) is located Y millimetres from the bottom surface (21) of the first mould part (15), and wherein Y > X.

7. The product forming unit (11) according to any preceding claim, wherein the cellulose blank (10) is composed of an air-laid cellulose blank.

8. Method for controlling a product forming unit (11) configured for dry manufacturing rigid cellulose products (2) having essentially non-flat general shape from a cellulose blank (10), the product forming unit (11) comprising a moulding tool having a first mould part (15) and a second mould part (16), wherein at least one of the first mould part (15) and the second mould part (16) is displaceable in the axial direction in relation to the other in order to press the cellulose blank (10) therebetween into final shape by applying a predetermined pressure P in the axial direction of the moulding tool, wherein the first mould part (15) comprises a bottom surface (21) and the second mould part (16) comprises a bottom surface (19), the product forming unit (11) further comprising an out-feed device (25) having a movable arm (26) and a first suction device (27) connected to said arm (26), the method comprising the steps of:- providing the cellulose blank (10) into the moulding tool between the first mould part (15) and the second mould part (16),- displacing at least one of the first mould part (15) and the second mould part (16) in the axial direction in relation to each other, towards each other,- pressing the cellulose blank (10) between the first mould part (15) and the second mould part (16), wherein the axial distance between the bottom surface (21) of the first mould part (15) and the bottom surface (19) of the second mould part (16) during the pressing of the cellulose product (2) is T millimetres,- displacing at least one of the first mould part (15) and the second mould part (16) in the axial direction in relation to each other, away from each other,- inserting the first suction device (27) of the out-feed device (25) into the moulding tool between the first mould part (15) and the second mould part (16),- displacing the first suction device (27) towards the bottom surface (21) of the first mould part (15) in order to engage the cellulose product (2) and stopping at a stop position located X millimetres from the bottom surface (21) of the first mould part (15), wherein X > T and X < 3T, and- removing the rigid cellulose product (2) from the moulding tool using the first suction device (27) of the out-feed device (25).

9. The method according to claim 8, wherein the out-feed device (25) comprises a second suction device (29) connected to said movable arm (25), wherein the method comprises the steps of:- inserting the second suction device (29) of the out-feed device (25) into the moulding tool between the first mould part (15) and the second mould part (16), in order to engage the cellulose product (2) together with the first suction device (27),- displacing the second suction device (29) towards the bottom surface (21) of the first mould part (15) in order to engage the cellulose product (2) and stopping at a stop position located Y millimetres from the bottom surface (21) of the first mould part (15), wherein Y > T and Y < 3T, and - removing the rigid cellulose product (2) from the moulding tool using the first suction device (27) and the second suction device (29) of the out-feed device (25).

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