Patent Application
20250052005
The present disclosure relates to a method and an apparatus for forming an air-formed cellulose blank structure for producing a cellulose product, wherein the method comprises the steps of providing a flow of cellulose-based material to a mill, defibrating the cellulose-based material in the mill into cellulose fibres, providing an air-formed cellulose blank structure, wherein the cellulose blank structure is air-formed from the cellulose fibres.
Cellulose fibres are often used as raw material for producing or manufacturing products. Products formed of cellulose fibres can be used in many different situations where there is a need for having sustainable products. A wide range of products can be produced from cellulose fibres and a few examples are disposable plates and cups, blank structures and packaging materials.
Forming moulds are commonly used when manufacturing cellulose products from raw materials including cellulose fibres, and traditionally the cellulose products have been produced with wet-forming technologies. A material commonly used for cellulose fibre products is wet moulded pulp. Wet moulded pulp has the advantage of being considered as a sustainable packaging material, since it is produced from biomaterials and can be recycled after use. Consequently, wet moulded pulp has been quickly increasing in popularity for different applications. Wet moulded pulp articles are generally formed by immersing a suction forming mould into a liquid or semi liquid pulp suspension or slurry comprising cellulose fibres, and when suction is applied, a body of pulp is formed with the shape of the desired product by fibre deposition onto the forming mould. With all wet-forming technologies, there is a need for drying of the wet moulded product, where the drying is a time and energy consuming part of the production. The demands on aesthetical, chemical and mechanical properties of cellulose products are increasing, and due to the properties of wet-formed cellulose products, the mechanical strength, flexibility, and chemical properties are limited. It is also difficult in wet-forming processes to control the mechanical properties of the cellulose products with high precision. One development in the field of producing cellulose products is the forming of cellulose fibres without using wet-forming technologies, and instead the cellulose products are produced in a dry-forming process. In the dry-forming process, an air-formed cellulose blank structure is used. The air-formed cellulose blank structure is inserted into a forming mould and during the forming of the cellulose products the cellulose blank structure is subjected to a high forming pressure and a high forming temperature.
When using cellulose products made according to the dry-forming process, the cellulose products may be exposed to liquids, food or other substances that may affect the stiffness and rigidity of the cellulose products due to the tendency of the formed cellulose products to absorb for example water, moisture, or other substances. Plastic films that are laminated to the cellulose products may be used for preventing liquid from affecting the cellulose products. However, with the demand for more environmentally friendly products there is a desire to produce the cellulose products without plastic materials.
There is thus a need for an improved method for producing cellulose products from an air-formed cellulose blank structure, where the cellulose products can be produced to resist contact with liquids, food and other substances for longer time periods without affecting the mechanical properties of the cellulose products. There is further a demand for certain types of products to hold liquids or food, where no harmful substances are added to the cellulose products.
An object of the present disclosure is to provide an improved method and apparatus for producing a cellulose blank structure and a method for producing a cellulose product where the previously mentioned problems are avoided.
This object is at least partly achieved by the features of the independent claims. The dependent claims contain further developments of the method for producing a cellulose product and the cellulose product.
The description below will refer to Scala as a collective name for a machine for producing a cellulose product according to the invention, where the machine will comprise a variety of parts that will be explained below and in connection to the drawings.
The invention relates to a method for forming an air-formed cellulose blank structure for producing a cellulose product, wherein the method comprises the steps;
One advantage with the method is that the synchronization allows for a compact machine with high control of all process steps. In a stationary mode, the conveyor belt is arranged in a standstill state such that the cellulose blank structure is formed on an at least partly non-moving conveyor belt. Here, it should be understood that the cellulose blank structure can be formed onto the conveyer belt only when the conveyer belt is in a standstill, or alternatively is formed when the conveyer belt moves into the standstill and during the standstill, or alternatively is formed during the standstill and when the conveyer belt moves from the standstill, or alternatively is formed when the conveyer belt moves into the standstill and during the standstill and when the conveyer belt moves from the standstill. In yet another example, the cellulose blank structure can be formed onto the conveyer belt only when the conveyer belt is moving, i.e. synchronized with the forming mould to allow forming of the cellulose blank structure between two pressing operations. The duration of the standstill state is synchronized with the duration of the pressing operation such that the standstill state is occurring during the pressing operation. The conveyor belt may be arranged in the standstill state at any time during pressing operation, and the time duration of the standstill state may be only a part of the time duration of the pressing operation, or alternatively the full pressing operation. I.e., the conveyor belt is synchronized to intermittently be in a standstill state during parts of or the whole of the application of a forming pressure onto the cellulose blank structure in the forming mould. The conveyor belt is advantageously an air permeable forming wire configured in a position close to the suction box on one side and the web forming on the opposite side. The suction box creates an under-pressure on the forming wire that creates an airstream in a direction towards the suction box, such that that the fibres are formed into the cellulose blank structure onto the forming wire.
According to one advantageous example, the step of providing the cellulose blank structure to a forming mould comprises the step of feeding the cellulose blank structure essentially vertically.
This has the advantage of a small and compact machine.
According to one advantageous example embodiment, the step of intermittently operating the forming mould to apply a forming pressure onto the cellulose blank structure, comprises the step of operating the forming mould in a horizontal pressing stroke.
This has the advantage of a small and compact machine, especially together with vertically fed cellulose blank structure.
According to one advantageous example embodiment, the method comprises a step of cutting out the cellulose product from the cellulose blank structure in and/or after the forming mould, thereby forming a residual cellulose fibre structure of the remaining cellulose blank structure, and feeding the material of the residual cellulose fibre structure to the mill as a complement to the flow of cellulose-based material.
According to one example embodiment, the method comprises the step of providing a first tissue layer onto one side of the cellulose blank structure, wherein the first tissue layer preferably comprises a barrier chemistry composition, hereinafter called BCC.
According to one example embodiment, the method comprises the step of providing a second tissue layer to one side of the cellulose blank structure, wherein the second tissue layer preferably comprises a barrier chemistry composition, BCC.
According to one example embodiment, the barrier chemistry composition is provided to the first and/or second tissue layer during production and/or the step of providing the barrier chemistry composition to the first and/or second tissue layer by providing the barrier chemistry composition before production.
One advantage with pre-prepared tissue, is that the pre-prepared tissue has a controlled and specific amount of BCC that makes it easy to calculate the amount of BCC in the end product by the controlling the material ratio in the mill and/or in the forming hood. Another advantage is that a pre-prepared tissue removes the need for a BCC spray unit and thus removes cost and the need for maintenance of the spray box.
According to one example, the first tissue can be positioned on one side of the cellulose web structure and the second tissue can be on the opposite side of the cellulose web structure. This has the advantage that the product can be designed with one type of tissue layer on one side, e.g. an inside of a product, and another type of tissue layer on the other side, e.g. the outside, giving the product two sides with different properties. It should however be noted that the same type of tissue can be used as the first and the second tissue, giving similar properties on both sides of the product. Furthermore, the first and second tissue can be applied on the same side and if suitable, a third or more tissue can be applied on the same or the opposing side.
The use of a tissue added to the cellulose web structure has the further advantage that the BCC in the recycled residual cellulose fibre structure is mixed with the defibrated cellulose-based material in the mill giving the cellulose web structure an amount of BCC embedded in the structure, but also a tissue layer forming an outer layer of the product that can have a higher amount of BCC giving a higher degree of barrier properties than the core without exceeding the maximum amount BCC in the end product. The higher amount of BCC in the outer barrier layer gives a first barrier property that hinders a liquid from penetrating the barrier layer, but the BCC in the core of the product, i.e. in the part of the product essentially made from the cellulose web structure, gives further barrier properties also if the liquid penetrates the outer barrier that hinders disintegration of the core of the product.
It should be noted that when adding a first and/or second tissue to the cellulose web structure, then reference to feeding, forming, cutting and curing of the cellulose web structure relates to the entire composition of cellulose web structure and added tissue(s).
It should be noted that the first and/or second tissue layers can be free from BCC.
According to one example embodiment, the step of providing the cellulose blank structure to a forming mould comprise the step of heating the cellulose blank structure to a forming temperature in the range of 100° C. to 300° C. at least in the mould, and forming the cellulose product from the cellulose blank structure in the forming mould, by pressing the heated cellulose blank structure with a forming pressure of at least 1 MPa, preferably 4-20 MPa, and cutting out the cellulose product in and/or after the forming mould from the cellulose blank structure forming a residual cellulose fibre structure of the remaining cellulose blank structure that can be fed back to the mill.
According to one example, the residual cellulose fibre structure is recycled by feeding the material of the residual cellulose fibre structure to the mill as a complement to the cellulose-based material.
According one example embodiment, the step of feeding the material of residual cellulose fibre structure to the mill comprises feeding the residual cellulose fibre structure directly to the mill, i.e. without further defibration, via a transport unit.
One advantage here is that only one mill, i.e. the mill, can be used for the entire operation thereby reducing cost and maintenance. A calendaring apparatus can be used to hard compact the recycled residual fibre structure, which has shown to give a good defibration. It should be noted that a calendaring apparatus in connection to the second opening of the forming hood can be to give an improved transporting ability of the cellulose blank structure.
According to one example embodiment, the method comprises the step of providing a barrier chemistry composition to the cellulose-based material before production and/or in production.
According to one example embodiment, the step of air-forming comprises the step of feeding the conveyer belt vertically such that the fibres are fed to the conveyer belt horizontally.
The invention further relates to a cellulose product machine, also called Scala in the description, for performing the method according to any one of the preceding claims, wherein the machine is configured to form an air-formed cellulose blank structure for producing the cellulose product, wherein the machine comprises a first transport unit, a mill, a forming hood, a conveyer belt, a suction box, a second transport unit and a forming mould, wherein the first transport unit is configured to
The advantage with the cellulose product machine is the same as described for the method above.
According to one example embodiment, the second transport unit is configured to provide the cellulose blank structure to the forming mould vertically.
According to one example embodiment, the forming mould is configured to operate in a horizontal pressing stroke.
According to one example embodiment, the conveyer belt is configured to run vertically such that the fibres are fed to the conveyer belt (111) horizontally.
All vertical operations have the advantage of a small and compact machine.
The overall objective with Scala is to enable rapid global scaling of Dry Moulded Fibre as a replacement for single use plastics by lower manufacturing cost, lowering CO2 emissions, lowering energy and water consumption, reduce footprint, and enable serial production of a stand-alone plug-and-play machines in different sizes and performance.
Injection Moulding Machines (IMM) for moulding thermo plastics is serial produced in a global volume of over 100 000 machines per year. Except for the extruder, an IMM performs and operates similar to the presses used in Dry Moulded Fibre lines. Same range of press (clamping) forces, same range of cycle time, normally including force control, ejector, and heating of tools. Most IMM has horizontal pressing direction that enable lower machines heights compared to previous used horizontal steel presses.
According to one example, the step of providing BCC comprises the step of providing BCC to the cellulose-based material before production and/or in production.
According to one example, the step of providing BCC to the cellulose-based material before production comprises the step of pre-treating the cellulose material partly with BCC forming a sectioned cellulose-based material partly comprising BCC and/or where the step of providing BCC to the cellulose-based material in production comprises the step of providing BCC to selected parts of the cellulose material forming a sectioned base cellulose material partly comprising BCC.
It should be noted that pre-treatment refers to any type of addition of BCC to the cellulose-based material, but it is of utmost importance that the BCC is not dispersed in the cellulose-based material such that most or all of the fibres in the cellulose-based material is contaminated since this would jeopardize the possibility to form hydrogen bonds when forming the product. Hence, the BCC could be added to the cellulose-based material e.g. as an additional layer to the cellulose-based material and/or strands of BCC in the cellulose-based material, just as long as there is a significant portion of fibres not contaminated with BCC. The mill will defibrate all fibres and some of the fibres will have BCC attached, but at least a significant part of the fibres should be void of BCC such that a suitable blend/mix of fibres are air-formed into the cellulose blank. Should the process be arranged such that there will be no recycling of the residual cellulose fibre structure, then the amount of BCC in the cellulose-based material governs the amount of BCC in the end product unless one or more tissues with BCC are added to the cellulose blank structure. In the latter case, the total amount of BCC has to be calculated in order to not exceed the predetermined maximum value of BCC in the end product. For similar reasons, any addition of BCC in the process has to be taken into consideration.
According to one example, the step of providing BCC to the cellulose-based material in production can be realized by adding spray BCC to the cellulose-based material before the mill and/or an extra flow of cellulose-based material comprising BCC. If the process uses two or more flows of cellulose-based materials to the mill, then at least one of the flows can be void of BCC and one or more may comprise a large amount BCC since the mix of the flows in the mill gives an adequate mix of BCC treated fibres and fibres with no BCC attached. Should the process be arranged such that there will be no recycling of the residual cellulose fibre structure, then the amount of BCC in the cellulose-based material or materials governs the amount of BCC in the end product unless one or more tissues with BCC are added to the cellulose blank structure. In the latter case, the total amount of BCC has to be calculated in order to not exceed the predetermined maximum value of BCC in the end product. For similar reasons, any addition of BCC in the process has to be taken into consideration.
According to one example, the cellulose-based material is pre-treated partly with BCC, which has the advantage of removing the need for spray BCC. The BCC in the cellulose-based material will be part of the cellulose blank structure and can be recycled with the residual cellulose fibre structure, either via a second mill or directly to the mill according to the above. The recycled BCC in the recycled residual cellulose fibre structure together with the BCC in the cellulose-based material has to be controlled and the amount of cellulose-based material is controlled dependent on amount of recycled residual cellulose fibre structure, especially during the transient period. According to another example, the cellulosed-based material is treated with spray BCC before the mill, which has the advantage of controlling the BCC dependent on amount of recycled residual cellulose fibre structure, at least in the transient period.
The disclosure regarding the machine hereinafter called Scala will be described in detail in the following, with reference to the attached drawings, in which
Various aspects of the disclosure will hereinafter be described in conjunction with the appended drawings to illustrate and not to limit the disclosure, wherein like designations in many cases are different for like elements, and variations of the described aspects are not restricted to the specifically shown embodiments, but are applicable on other variations of the disclosure.
The description below will refer to Scala as a collective name for a machine for producing a cellulose product according to the invention, where the machine will comprise a variety of parts that will be explained below and in connection to the drawings.
The invention relates to a method for forming an air-formed cellulose blank structure 102 for producing a cellulose product 101, which is shown in various aspects in
One advantage with the method is that the synchronization allows for a compact machine with high control of all process steps. In a stationary mode, the conveyor belt is arranged in a standstill state such that the cellulose blank structure is formed on an at least partly non-moving conveyor belt. Here, it should be understood that the cellulose blank structure can be formed onto the conveyer belt only when the conveyer belt is in a standstill, or alternatively is formed when the conveyer belt moves into the standstill and during the standstill, or alternatively is formed during the standstill and when the conveyer belt moves from the standstill, or alternatively is formed when the conveyer belt moves into the standstill and during the standstill and when the conveyer belt moves from the standstill. In yet another example, the cellulose blank structure can be formed onto the conveyer belt only when the conveyer belt is moving, i.e. synchronized with the forming mould to allow forming of the cellulose blank structure between two pressing operations. The duration of the standstill state is synchronized with the duration of the pressing operation such that the standstill state is occurring during the pressing operation. The conveyor belt may be arranged in the standstill state at any time during pressing operation, and the time duration of the standstill state may be only a part of the time duration of the pressing operation, or alternatively the full pressing operation. I.e., the conveyor belt is synchronized to intermittently be in a standstill state during parts of or the whole of the application of a forming pressure onto the cellulose blank structure in the forming mould. The conveyor belt is advantageously an air permeable forming wire configured in a position close to the suction box on one side and the web forming on the opposite side. The suction box creates an under-pressure on the forming wire that creates an airstream in a direction towards the suction box, such that that the fibres are formed into the cellulose blank structure onto the forming wire.
According to one advantageous example, the step of providing the cellulose blank structure 102 to a forming mould 105 comprises the step of feeding the cellulose blank structure 102 essentially vertically.
This has the advantage of a small and compact machine.
According to one advantageous example embodiment, the step of intermittently operating the forming mould 105 to apply a forming pressure onto the cellulose blank structure 102, comprises the step of operating the forming mould 105 in a horizontal pressing stroke.
This has the advantage of a small and compact machine, especially together with vertically fed cellulose blank structure.
According to one advantageous example embodiment, the method comprises a step of cutting out the cellulose product 101 from the cellulose blank structure 102 in and/or after the forming mould 105, thereby forming a residual cellulose fibre structure 110 of the remaining cellulose blank structure 102, and feeding the material of the residual cellulose fibre structure 110 to the mill 104 as a complement to the flow of cellulose-based material 106.
According to one example embodiment, the method comprises the step of providing a first tissue layer 106a onto one side 102a of the cellulose blank structure 102, wherein the first tissue layer 106a comprises a barrier chemistry composition.
According to one example embodiment, the method comprises the step of providing a second tissue layer 106b to one side 102b of the cellulose blank structure 102, wherein the second tissue layer 106b comprises a barrier chemistry composition.
According to one example embodiment, the barrier chemistry composition is provided to the first and/or second tissue layer during production and/or the step of providing the barrier chemistry composition to the first and/or second tissue layer by providing the barrier chemistry composition before production.
According to one example embodiment, the method comprises the step of step of providing a barrier chemistry composition to the cellulose-based material 106 before production and/or in production.
According to one example embodiment, the step of air-forming comprises the step of feeding the conveyer belt 111 vertically such that the fibres are fed to the conveyer belt 111 horizontally.
The invention further relates to a cellulose product 101 machine 100, also called Scala in the description, which is shown in various aspects in
In a stationary mode, the conveyor belt is arranged in a standstill state such that the cellulose blank structure is formed on an at least partly non-moving conveyor belt. Here, it should be understood that the cellulose blank structure can be formed onto the conveyer belt only when the conveyer belt is in a standstill, or alternatively is formed when the conveyer belt moves into the standstill and during the standstill, or alternatively is formed during the standstill and when the conveyer belt moves from the standstill, or alternatively is formed when the conveyer belt moves into the standstill and during the standstill and when the conveyer belt moves from the standstill. In yet another example, the cellulose blank structure can be formed onto the conveyer belt only when the conveyer belt is moving, i.e. synchronized with the forming mould to allow forming of the cellulose blank structure between two pressing operations. The duration of the standstill state is synchronized with the duration of the pressing operation such that the standstill state is occurring during the pressing operation. The conveyor belt may be arranged in the standstill state at any time during pressing operation, and the time duration of the standstill state may be only a part of the time duration of the pressing operation, or alternatively the full pressing operation. I.e., the conveyor belt is synchronized to intermittently be in a standstill state during parts of or the whole of the application of a forming pressure onto the cellulose blank structure in the forming mould. The conveyor belt is advantageously an air permeable forming wire configured in a position close to the suction box on one side and the web forming on the opposite side. The suction box creates an under-pressure on the forming wire that creates an airstream in a direction towards the suction box, such that that the fibres are formed into the cellulose blank structure onto the forming wire.
According to one example embodiment, the second transport unit 109 is configured to provide the cellulose blank structure 102 to the forming mould vertically.
According to one example embodiment, the forming mould 105 is configured to operate in a horizontal pressing stroke.
According to one example embodiment, the cellulose product 101 machine according to any one of the preceding claims 10-12, wherein the conveyer belt 111 is configured to run vertically such that the fibres are fed to the conveyer belt 111 horizontally.
The above will be further described in connection to
Plundering is performed in similar way as in an IMM, see
Important functionality of the covers is to lower noise and protect operators from injuries. Access to the machinery for maintenance and service is also a functional requirement on the cover/housing design, see 1.4.
Scala should be approved and CE-marked for any sales within the European Economic Area (EEA).
Machine weight, excluding Pulp and tissue equals ca 10 ton
Delivered partly de-mounted in a 40 ft Shipping Container (12.2×2.4×2.6 height m)
The machine ejects 5000 m3/hrs. of air (containing max 2 kg fibres/hrs when using full capacity) from the Vacuum Fan outlet. A central dust filter is needed for one or several Scala.
The Operators HMI comprises:
Scala offers seven easy access openings for operators and service.
For more access at service and maintenance cover panels can be detached, see chapter 2.5 Covers Sub-System.
The operational functions, from Pulp In to finished Fibre Product, is described in the flowchart in
This document uses the following nomenclature shown in
This Chapter of the Specification, introduces all Sub-Systems, their sub-ordinary Units, and all included Modules, controlled via the PLC.
However, Scala has five main physical sub-assemblies (except for the covers), that deviates from the Sub-Systems to some extent, i.e. the Vacuum Fan is mounted in the Tissue sub-assembly and the HMI is mounted on top of fibre supply sub-assembly in the MTW roof top cover. There is also a fibre sub assembly framework that hosts the Mill-to-Web Sub-System and the Recycling Sub-System, see
In the following, this document will present and describe the Sub-Systems (i.e., without covers and without concern of sub assembly architecture).
Scala is design and manufactured as a versatile fibre moulding machine for any type of fibre product. However, the first Scalas will be sold with tooling for a specific fibre product and this document introduces the tool design as a part of the Clamping Unit Sub-System in chapter 2.3.
Scala comprises Six Sub-Systems:
Each of these sub-systems, with its sub-units, will be described and specified in the following.
Each Module is named using the following nomenclature:
Besides the Clamping Unit/Moulding Sub-System, the Mill-to-Web (MTW) constitutes the main sub-system of Scala. The MTW converts raw pulp (P: 1) into a fluffy loose fibre web and supply this material, as a pre-compacted web (P: 2) by and adding tissue on top and bottom in the kissing point (KP), before feed into the tool. The Saw tooth Mill (1:2) breaks up almost all hydrogen bonds in the pulp sheet (P: 1). A Vacuum Fan (1:5) draws/sucks all loose fibres through the Mill, via a Fibre Formation Hood 1:3 onto a moving wire using a vacuum suction box in the Web Forming Subunit (1:4).
The Compression Roller (1:4.4) and the Feeder Roller (1:4.2) are both driven by Servo Motor (MS4). Both Servo Motors (MS3 and MS4) are mounted inside at the top of the Web Forming Unit underneath the wire. The Wire (1:4.1) tension is manually adjusted by the two screws (WT).
Scala has no buffer between the Mill-to-Web and the Moulding Sub-System. I.e., all Servo Motors (MS3, MS4, MS7, MS8, MS9 and MS10) operates simultaneously in a Stop-and-Go sequence. However, the Pulp and Tissue rolls has too much torque inertia to be operated at Stop-and-Go why (MS1, MS2, MS5 and MS6) operates at continuous speed. The same goes for the Recycling Sub-System (4), see Chapter 2.4.
Since booth virgin Pulp and Waste Web are feed continuous into the Mill (MA1), the fibres will be drawn to a non-moving wire most of the cycle sequence, see diagram above. I.e., one sheet, approximately 500×500 mm of Web will be accumulated on the wire before feeding towards the moulding area starts.
A certain overlap between each Web Sheet will locally affect the Basis Weight GSM (gram per square meter).
The Web Forming Subunit (1:4) also holds rollers (TR) to guide the Lower Tissue path under the Suction Box and up to the Kissing Point (KP) where the Fibre Web meets the upper and lower tissue.
The Wire Belt (1:4.1) may drift sidewise (wandering) on the rollers, when running, why the Web Forming Unit is equipped with a simple and autonomous pneumatic feedback control system for Wire Tracking,—not part of the PLC-control. A pivot pin (SI3) trailing on the edge of the Wire (1:4.6), see red ring in
The dotted arrows in
The Web (P: 2) leaving the Mill-to-Web Sub-System (1) should be layered with a Upper Tissue (TU) and a Lower Tissue (TL), at the Kissing Point (KP), before entering the Tool Feeder.
In most applications, where the fibre product requires barriers towards water and/or oil, the tissue is pre-coated with a small amount (<1% w.) of sustainable barrier chemistry, e.g., AKD wax. When formed in the tool, using high pressure and high temperature, the barrier chemistry will penetrate into the fibres (1:2) and seal the fibres to create the desired properties of the final fibre product. In some cases, after-curing might be needed to obtain full barrier properties.
In other cases the converter (customer) might preferred coloured or pre-printed tissue to enhance the aesthetic properties of the finished fibre product.
In contrast to the Pulp (P: 1) the Tissue (P: 3) is a thin a fragile paper sheet that easily breaks if path tension is too high. In order to ensure a tissue tension of 10-100N the Tissue Sub-System is equipped with driven Tissue Roll Axis (2:1) where the Tissue Roll is manually clamped with a Toggle Handle (2:2). Each roll is driven by a Servo Motor (MS5/MS6) via a worm gear (2:8) and controlled in a feedback loop in PLC using a Tissue Buffer & Tension Pivot Sensor (Dance arm) (2:4, 2:9 and SA 1), see
The Fan (1:5) belongs functionally to the Web Forming Sub-Unit, see 2.1.3 but is mounted on Tissue Framework (2:7) and is shown in these figures as part of this Sub Assembly.
The Pivot Roller (2:4) rests with a small contact force (FT) inside a tissue loop, se fig. XX above, and pivots around the Tissue Roll Axis (2:1) with a Pivot Arm (2:9). The Pivot Arm has one longer arm, outside the cover plate, see chapter 2.5, and one shorter arm on the inside of the cover plate.
The shorter arm is connected to a pneumatic cylinder (2:5), that balances the weight of the Pivot Arm (2:9 & 2:4) to the correct contact force (FT), and a linear potentiometer, the Tissue Buffer & Tension Sensor (SA1 & SA2) that measures the position of the Pivot Roller (2:4), i.e., the amount of tissue in the buffer. This value is then feedbacked looped to the regulator for the Servo Motor (MS6) to rotate the tissue roll in the right speed to maintain the buffer needed. The tension of the tissue (10 and 100N) is manually set by the pneumatic cylinder (2:5).
Each Tissue roll is lasting around 10 hours in continuous production. Two sensors (laser—SA3 and SA4), see
The Moulding Sub-System comprises three Sun-Units:
On the following described and specified one by one. (The two Tissue Rollers (TR) shown in Fig. belongs to the Mill-to-Web Sub-System and is shown as a reference for the Kissing-Point (KP).)
The Clamping Unit (3:1) in Scala is a standard clamping unit from an injection moulding machine, i.e., a horizontal press, and will not be described in detail in this document. However, the main components of this sub-unit are:
The force and movement from the hydraulic Clamping Cylinder (Fh) (3:1.7) is transferred by the toggle arms into an exponential movement with high speed and low force near the open set and low speed and high force near the closed see (β=180°).
In order to secure a reliable and controlled feeding of the Web (P: 2) with Tissue to the Tool (3:3) and Waste Web out of the tool area, two Feeder Sub-Units (3:2), with two servo Motors each, are used:
Each Feeder (3:2) is equipped with two pneumatic cylinders (3:2.2) that creates a nip force (WN) between the two rubber coated rollers (3:2.1). The pressure of the cylinders is manually adjusted on a regulator and manually opened by a valve for service and threading of new web.
The Upper Web Feeder and the Lower Web Feeder are almost identical, why a general Feeder (3:2) is described here. The Upper Feeder should however be possible to move into a service position (SO) when loading and un-loading tools.
Scala is designed for intermittent feeding of the Web, in the following called Stop-and-Go. Since earlier Fibre Moulding Machines has been based on continuous forming of the web, a buffer system may accumulate enough web length to be able to allow the Web feeder to rapidly feed new web into the tool area.
Scala has no buffer between the Mill-to-Web and the Moulding Sub-System. I.e., all Servo Motors (MS3, MS4, MS7, MS8, MS9 and MS10) operates simultaneously in a Stop-and-Go sequence. However, the Pulp and Tissue rolls has too much torque inertia to be operated at Stop-and-Go why (MS1, MS2, MS5 and MS6) operates at continued speed. The same goes for the Recycling Sub-System (4), see next chapter.
Each Feeder (3:2) uses two Feeder Rollers (3:2.1) and two Servo Motors (MS7 and MS8; for the upper Web Feeder and MS9 and MS10; for the lower Waste Feeder). The reason for double Servo Motors in each feeder is the need for adjusting the rotation speed individual on the two roller. Layered Tissue tends to bulge out from the Web (P: 2) and also the entire Web is a fluffy and organic material that might require different peripheral roller surface speed to not be damage by shear stress. The different might be very small and is set in the HMI upon loading of new material and basis weight.
One Feeder Roller Assembly is built inside a dia. 170 mm rubber coated sleeve roller (3:2.1). A drive flange (3:2.7) is mounted inside the sleeve and the Servo Motor (MS7) with Planetary Gear (3:2.5) is inserted through Feeder Roller Gables (3:2.6). The Feeder Roller Assembly is guided on the Slide Bars (3:2.3) by Slide Guides (3:2.8).
Each Feeder Roller Assembly pair can be adjusted in the sliding direction to feed the Web on a proper distance from the Tools in open state. I.e., manual adjustment needed for each tool with new tool thickness.
A Female-(3:3.2) and a Male-(3:3.1) Tool System is respectively mounted on the Clamping Unit Moving Platen (3:1.2) and the Fixed Platen (3:1.1). The Moving Platen (3:1.2) is moved by the Toggle System and closes and opens the Tools, (thus temporary creating a gap (G) of the Tool Systems).
A tool for Dry Moulded Fibre requires additional know-how compared with the design of Injection Moulding Tools and/or Thermo Forming Tools for Thermo Plastics. This document is not covering design guidelines for tools for Scala. Please consult with a certified PulPac Tool Maker™ or directly to PulPac AB for guidance.
However, here follows an overview introduction, using a typical single use fibre lid, dia. 100 mm, as an example.
All tools are heated, normally using heat resistor inserts, to typically 150-180° C.
A multi cavity Tool (3:3) for Dry Moulded Fibre can preferably be made up of several single mould cavities (3:3.1 and 3:3.2). The single mould cavities are mounted on a Mother Plate (3:3.3) and an Insulator Plate (3:3.4) to decrease heat losses to the Clamping Unit.
The following description presents a single cavity mould, equipped with in-mould cutting, for producing a lid, e.g., for yogurt cups. Please note that the reference numbers in this description does not follow the general nomenclature in this document.
Many tools includes a spring loaded (5:6)) in-mould cutting device (5:5) and a soft pressure member, made by an Elastomer (5:7), assuring an isostatic pressure, i.e. essentially equal pressure in all directions, of at least 12 MPa, see diagram in
All tools are heated to a temperature (X15) measured by Tool Temperature Sensor (SAX) in every single tool. The Operator sets the desired Tool Temperature (SAX), in the “Product Recipe” in HMI and the PLC controls the measured temperature via a PID-regulator.
With reference to fig. previous page the forming process can be described in four steps A-D, normally taking 3 seconds per cycle.
The Blank Web width of 500 mm and the outer size of the Clamping Unit Platens of 815×815 mm defines the available area for a multi cavity tool system.
In most cases the available tool mounting area, see dotted rectangle in
X16=1 713 kN (173 ton); The Cut Force (F1) in this example is 20 kN/cavity
The preferred Forming Pressure (X14) or Pressure Force (X16) is defined in the product recipe section of the HMI.
The first Scala prototypes are using a Servo Hydraulic Clamping Unit HRU 300FC from Huarong Plastic Machinery Ltd.
The residual web (P: 3), after forming and punching out the products, including tissue coated with barrier chemicals, is possible to feed back to the Saw tooth Mill (1:2) for defibration again and re-use for new fibre products. The re-circulated fibres will reach a steady state level after a numbers of run and the milled tissue and additional levels of Barrier Chemicals will reach acceptable levels for forming and food grade approvals.
The waste web (P: 3) needs however to be hard compressed into a stiff sheet to be able to defibrate in the mill again, similar to the raw pulp. This compression is done in the Compression Unit followed by a transportation belt, constituting the Recycling Sub-System (4), see
Two Compression Rollers (4:1 and 4:2) are driven by Servo Motor (MS11) and a double-sided cog belt (4:3). The two rollers are supported by double roll bearings in each end, to withstand the Compression Force (Fc max=100 kN). The bearings of the Lower Roller (4:2) are supported by an Eccentric Ring (4:4) hosting a trapezoidal thread in its periphery. The Compression Force (Fc), or more correct, the geometrical distance between the two Compression Rollers are manually adjusted by turning a trapezoidal threaded Screw (4:5).
The roller distance can be adjusted between 0 and 4 mm. The thickness (t) of the Compressed Waste Web with Tissue (P: 3) will always be larger than the nip gap due to spring back in the fibre structure. A typical thickness of the Waste Web (t) is however 2-6 mm.
The Compression Rollers and the Mill Feeder are operated in a continuous motion and is not comprised by the Stop-and-Go motion in the Moulding Sub-System. I.e., a Waste Buffer, see previous fig., will store 0.5 m within each cycle. A Pivot Arm Sensor (SA3) measures the position of the Buffer Bulge to avoid Web path breakage.
A Belt Conveyor (4:6), driven by Servo Motor (MS12), transports the compacted Waste Web (P: 3) to the inlet of the Mill (1:2).
The functional purpose of the covers is to protect users from injuries and to lower noise less than 80 dB. Several sensors register the open/close status of openable covers and disable start-up or emergency stop the machine if opened in automatic mode.
The Spec. code in table above:
The glass in the Front Door (6:1) is made by Polycarbonate. The glass in MTW Front Door (6:2) is two layer insulation hardened and un-crushable in order to secure food safety.
The HMI Panel specification of Scala is:
The touch screen panel is mounted on a swing arm enabling the operator to elevate and tilt the panel in the horizontal plane for optimal access by the sliding door.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2151618-2 | Dec 2021 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/086132 | 12/15/2022 | WO |
