Variable slot gate bar and improved foaming and reactive resin film release system

Abstract

The invention relates to a variable slot gate bar for a reactive foaming or foaming system, comprising a flat first element and a second element having at least one flow recess. The first flat element and the second flat element are connected to the rear surface of the second element by means of at least one connecting device. The flat first element and the second element have a gap facing the front surface of the second element, defining a gate bar slot. The flattened first and second elements define an internal brake bar passage at the flow recess of the second element. A variable slot gate rod releases an exhaust flow of a chemical reactive mixture through the gate rod slot. The width of the gate bar slot can be automatically adjusted to control the pressure of the discharge flow. The invention also relates to a foaming or foaming system comprising a variable slot gate bar and a control system.

Description

Technical Field

[0001] The present invention generally relates to polyurethane mixtures for foaming or pre-expansion and to systems for releasing reactive resin films, particularly in the continuous production of rigid and flexible polyurethane foams, in the field of producing flexible foam slabs or rigid foam sheets.

[0002] More specifically, the present invention relates to a system suitable for controlling the pressure release and release shape of polyurethane reactive resins. Background Art

[0003] Generally, in polyurethane foam technology, carbon dioxide is the gas generated during the foam growth process and is the cause of the formation of the foam honeycomb structure.

[0004] In the foam, due to the partial reaction of isocyanate with water deliberately added to the polyol, CO is formed during the reaction of the polyol and isocyanate. 2 .

[0005] H 2 O reacts with the isocyanate to form the so-called "chemical CO 2 ", which is one of the bases for foam formation. However, this reaction also produces urea molecules, making the foam have a certain hardness, which is not always desirable because it causes some limitations to the softness and flexibility of the foam.

[0006] It is well known that the water content can be reduced by adding some physical blowing agents that contribute to expansion to the polyol.

[0007] The blowing agent can be a gas or a liquid with a boiling point not much different from room temperature. They are dispersed or dissolved in the polyol and are released during the reaction due to the decrease in solubility and the increase in temperature caused by the reaction itself.

[0008] Since CO 2 is a polar molecule, it is easily soluble in many liquids, including polyols, under a certain pressure. Before mixing CO 2 with the isocyanate to produce polyurethane through reaction, CO 2 can be dispersed and dissolved in the polyol matrix.

[0009] To allow the dissolution of the required amount, the polyol and CO 2 are held and metered under pressure and mixed by mechanical stirring in a static mixer.

[0010] The mixture of the polyol and CO 2 should be maintained under a certain pressure during the dispersion process and the mixture should be kept in a liquid state to avoid forming bubbles in the liquid.

[0011] When the pressure is released, the release of the gas and the formation of the foam begin.

[0012] The rate of gas evolution depends on the rate of pressure release.

[0013] Typically, the faster the bubbles form, the larger the bubbles that create the foam.

[0014] The bubbles in the soft foam produced in the blocks and slabs must be fine and very uniform to obtain a soft touch and lightness. On the contrary, large bubbles entering the foam matrix and a completely open cell structure must be avoided.

[0015] To obtain a fine honeycomb foam, the release of pressure should be well controlled in time and space.

[0016] Hennecke has proposed a technique for controlling the pressure release of physically foamed polyurethane foam with carbon dioxide, which is based on controlling the pressure drop by releasing pressure in a series of sufficiently fine meshes.

[0017] The applicant has proposed an alternative technique in Application No. EP0734830A2, namely release and laying through a "gate bar".

[0018] As a further application, the bar can be used to form a liquid film of a reactive resin with a uniform thickness, and this liquid film exits along the gaps and / or grooves of the bar itself.

[0019] The "gate bar" is a component composed of two parts, having a top inlet, a channel passing through the centers of the two bars, a pressure equalization and distribution chamber, and an outlet groove for the liquid polyurethane mixture, and this liquid polyurethane mixture is distributed over the entire production width to the pouring area of the slab production machine.

[0020] In other words, the "gate bar" is suitable for distributing the flow rate and balancing the pressure at the groove inlet, and distributing the liquid polyurethane mixture over the entire production width to the pouring area.

[0021] The outlet groove is determined by calculation, which depends on the pressure required in the system to maintain the solubility of CO 2 in a mixture of various other chemicals, or when CO 2 or other low-temperature boiling blowing agents are absent, to form a liquid resin film distributed along the longitudinal extension of the gate bar.

[0022] Typically, two gate bars are tightly connected by bolts.

[0023] The groove is set using a gasket combination.

[0024] The gasket can be composed of multiple layers to set the required opening of the gate on the front.

[0025] The development of this solution takes into account the existing foaming or pre-expansion techniques.

[0026] The latter technique using low-boiling blowing agents is difficult to implement because it is necessary to create appropriate conditions for the pre-expansion and distribution of the polyurethane mixture to avoid turbulent phenomena and to obtain a polyurethane foam with a uniform honeycomb structure, free of air bubbles, pinholes, and defects.

[0027] To solve these problems, Patent EP0645226B1 of Kripton company adopts a special laying device for the foaming and dispensing of polyurethane mixtures.

[0028] It consists of a tubular gate rod which has longitudinal grooves that extend transversely to the flow direction of the mixture and open towards the cavity of a diffuser defined by a series of side walls oriented in different directions to deflect the flow of the pre-expanded mixture when it exits from the dispenser or the grooves of the gate rod.

[0029] The outlet groove is determined by calculation, which depends on the pressure required to maintain the solubility of CO 2 in a mixture of various other chemicals.

[0030] This groove is set using a combination of gaskets to create mixing conditions within the same gate rod and the mixing device upstream of the foaming device, such that low-boiling blowing agents such as liquid CO 2 can remain in a dissolved state when mixed with the polyurethane components and allow the resulting mixture to flow to the foaming device.

[0031] In addition, in the foaming device, the release of the blowing agent and the foaming of the mixture in the diffuser must be carried out in a uniform and controllable manner to avoid possible turbulence when the polyurethane mixture expands.

[0032] When calculating the dimensions of the groove, it is necessary to consider the pressure required to keep the blowing agent in a dissolved state inside the mixing chamber and in the gate rod.

[0033] During the process of releasing the fluid and pressure, turbulence is generated in the diffuser, resulting in an irregular honeycomb structure of the foam, thus leading to the presence of air bubbles and large cavities.

[0034] Appropriate improvements have been achieved in stabilizing the foam expansion by widening the gap near the edge where the mixture gushes towards the diffusion cavity.

[0035] The chamber distributes the mixture flow in the transverse direction because the gate rod is provided with longitudinal grooves on one side, which have side surfaces extending transversely to the elongated pressure equalization chamber.

[0036] The "gate rod" located at the opposite edges of the pressure equalization chamber includes one or two longitudinal side surfaces that are appropriately inclined and diverge in the flow direction towards the diffusion cavity.

[0037] Through slots or gates and inclined and divergent surfaces, the mixture stream leaves the rod and heads towards the cavity of the diffuser, which includes a series of walls with different orientations to deflect the flow of the pre-expanded polyurethane and control the expansion of the foam before it is released into the open space of the walled conveyor when the foam expands at atmospheric pressure.

[0038] The gate rod is also used to control the flow of reactive chemicals, where foaming is carried out by stirring the resin and air under pressure, through emulsified air or nitrogen or other gases finely pre-dispersed in polyols or other components of the mixture.

[0039] All these features are known and have been fully tested and verified, but to this day, it is still necessary to mechanically set and fix the geometry of the slots and, in fact, control the pressure release of the equalizing chamber.

[0040] As mentioned above, this setting is achieved by precise spacers or shims installed between the surfaces of two components that make up the gate rod.

[0041] These spacers have a micron thickness and can be installed between two components connected by fastening screws in order to determine the very precise geometry and thickness of the slots and prevent shape errors and / or deformations that would affect the flow distribution along the longitudinal dimension of the gate rod.

[0042] Still crucial for this process is this preventive setting of the gate rod, which depends on the flow rate and forms the apparent viscosity. In fact, the viscosity can be defined as the apparent viscosity because during the release through the slots, the formation of bubbles changes the viscosity of the fluid flowing through the slots.

[0043] The apparent viscosity depends on the amount of CO 2 dissolved and on the type and temperature of the components, so it is not easy to pre-determine the setting of the shims and trial and error should be carried out to determine the correct setting.

[0044] In addition, after introducing the gate rod as a system for controlling the expansion formed by CO 2 tests and trials have been carried out to produce gate rods suitable for non-CO 2 grades.

[0045] This non-CO 2 method is adopted because the gate rod can bring potential benefits to the slab foam production industry.

[0046] The key points are as follows:

[0047] · The full-width distribution of reactive chemicals in the pouring area of the slab production machine;

[0048] · The residence time of the chemical in the gate bar is short, which means little or no accumulation of polyurethane in the gate bar;

[0049] · Due to the relatively short residence time in the gate bar, the chemical emerging from the gate bar still has a relatively low reactivity level, which means the viscosity is still relatively low, so it can be poured onto the surface to form a foam block, thus avoiding entrained air bubbles or the formation of pinholes and preventing defects such as pinholes in the finished foam block;

[0050] · By pouring the liquid in thin sheets, air bubbles are not entrained because the cross-section of the poured liquid is reduced compared to traditional pouring.

[0051] This non-CO 2 The gate bars have now been verified in a production environment and their performance is good, demonstrating the above advantages.

[0052] However, one of the main limitations of the actual gate bars is due to the slot settings.

[0053] The slot width sets the back pressure in the mixing head.

[0054] In the non-CO 2 rating, the mixing head pressure can be in the range of 0.25 to 2.5 bar. The pressure in the mixing head directly affects the cell size of the polyurethane foam, which means the higher the pressure in the mixing head, the larger the cell size produced.

[0055] For the current CO 2 gate bars, the slot height is set using spacers. Although the effect is good, it limits the production capacity. As is well known, polyurethane foam producers hope to run their production machines for as many hours as possible per day because the greatest waste in continuous production machines occurs during startup and shutdown. To form a liquid film and lay it on a moving surface to form a slab block, it is very important that the thickness of the film and the specific flow rate along the extension of the gate bar remain constant. This requires the slots to have a uniform height and cross-sectional shape along the length of the bar.

[0056] In addition, as is well known, polyurethane foam producers hope to produce different grades of foam in a single production process to minimize waste again. Each different foaming formulation has its own characteristics in terms of reactivity, viscosity, specific gravity, etc.

[0057] In addition, modern systems for providing fluid for producing foam slabs require the ability to adjust and change the flow rate during production.

[0058] Since continuous slab polyurethane production machines require complete flexibility, laying devices with fixed outlet parameters, i.e., fixed gate bar slot height, are no longer suitable for additional requirements. Summary of the Invention

[0059] Accordingly, an object of the present invention is to provide a device which can not only adapt the opening height of the gate rod groove to the static setting of the flow rate to overcome the need for very precise setting of the above-mentioned spacer, but also can be adjusted according to the changes in the flow rate and pressure of the reaction mixture reaching the equalizing channel from the mixing head.

[0060] Another object is to provide a device for dispensing a pre-expanded polyurethane mixture, which has improved functions, can provide uniform mixture laying conditions, and can obtain bubble-free polyurethane foam with commercially acceptable quality within a wide range of production values.

[0061] Another object is to provide a device that allows fine control of the discharge flow.

[0062] Another object is to provide a device with a simple structure to avoid structural problems of products not suitable for mass production.

[0063] Finally, another object is to provide a device that is easy to implement in an existing system.

[0064] The solution idea of the present invention is to provide a gate rod, in which the groove should maintain a flat wall, and the flat wall is arranged in the longitudinal section to have the same geometry as the groove, but the height or opening of the groove should also be adjustable to adapt to the flow rate and / or pressure in the equalizing channel.

[0065] The above technical problem is solved by a variable groove gate rod for a foaming or foaming system, which includes: a flat first element and a second element, the second element having at least one flow recess distribution channel, and the flat first element and the second element are connected at the rear surface of the second element through at least one connecting device.

[0066] There is a gap between the flat first element and the second element, and the gap faces the front surface of the second element, thereby defining a generally longitudinal gate rod groove and defining an inner gate rod flow distribution channel for flow distribution at the flow recess of the second element.

[0067] The variable groove gate rod is adapted to release the discharge flow of the chemically reactive mixture through the gate rod groove, and the height or opening of the groove can be automatically adjusted, or in other words, can be set by appropriate control means to control the pressure of the discharge flow at the distribution channel.

[0068] The total flow rate of the reactive resin is set and controlled by the control system of the pump supplying the gate rod.

[0069] As for their mutual arrangement, the two surfaces of the groove should be longitudinally aligned during setting and during possible counter-deformation related to the pressure acting in the equalizing distribution channel and along the surface of the groove itself, and have a constant cross-section of the groove itself.

[0070] Advantageously, the present solution allows the slots to be opened uniformly and precisely according to each specific pressure condition, without the need for continuous critical manual operation by the operator to correctly set the height of the slots.

[0071] According to one embodiment of the present invention, the variable slot gate bar further comprises at least one pressurized stroke cylinder having a corresponding piston, preferably further comprising precision sliding bores and pins adapted to move a flat first element relative to a second element up and down to adjust the height of the gate bar slot.

[0072] Advantageously, from a structural point of view, the present solution is simple, but at the same time allows the height of the slot to be changed according to small clearances as well as according to the pressure inside the distribution channels and the slots themselves.

[0073] Preferably, the variable slot gate bar further comprises a blade support hinge to allow the flat first element to pitch and rotate relative to the second element, thereby adjusting the width of the gate bar slot.

[0074] The blade support hinge is an effective and reliable hinge system that does not produce any clearances and any friction during long-term use.

[0075] Preferably, the variable slot gate bar further comprises at least one conical spring system having a conical spring or a stack of conical springs and having a fastening screw for applying a load preload.

[0076] Advantageously, the solution provides another element for obtaining a controlled change in the slot opening.

[0077] More preferably, the variable slot gate bar further comprises at least one ball transfer bearing bracket or at least one circular ball bearing for transferring the pitching force between at least one piston and the flat element of the variable slot gate bar.

[0078] Advantageously, this allows for the correct distribution of the load and the correct movement between the components.

[0079] According to an alternative embodiment, the second element comprises a setting and control recess for the control element, and the variable slot gate bar further comprises a flexible bladder located in the setting and control recess, between the flat first element and the second element, controlled by air pressure or liquid pressure, and adapted to produce a force balance and control of the pressure in the flow distribution channel of the variable slot gate bar.

[0080] The bladder can be inflated through a tube inserted into the bottom of the bladder.

[0081] According to another embodiment, the variable slot gate bar further comprises: a Z-shaped or C-shaped joint that forms an elastic and gapless pitch hinge in the shape of an elastic fork element along the entire longitudinal dimension of the flat first element; and a flat and elastic metal tube that is pressed into the front groove of the elastic and gapless hinge.

[0082] Advantageously, the tube is supplied with hydraulic pressure and it can expand and push to close the gate bar slot.

[0083] According to another embodiment, the variable slot gate bar further comprises a motor-controlled hinge for moving the flat first element up and down relative to the second element, thereby adjusting the height of the gate bar slot.

[0084] Advantageously, the motor-controlled hinge is directly connected to the two gate bar parts through a gearbox to quickly respond to all pressure changes within the gate bar.

[0085] According to another embodiment, the variable slot gate bar further comprises a hydraulically controlled piston and at least one hinge that is applied between the extensions of the flat first element and the second element, wherein the flat first element is adapted to rotate around the hinge according to the action of the hydraulically controlled piston.

[0086] Advantageously, the hinge is well aligned by a tool, and the common part of the shaft is used to control the rotation of the upper part during operation.

[0087] According to a preferred embodiment, the variable slot gate bar further comprises a lever mechanism that is connected to the flat first element and the extension of the second element connected by a hinge, and is adapted to control the rotation of the flat first element and allow for more precise control of the gate bar slot.

[0088] According to another embodiment, the variable slot gate bar further comprises a hydraulically controlled piston and a sliding hook head that is connected to the hydraulically controlled piston and includes a plurality of inclined surfaces that slide against corresponding inclined lifting surfaces.

[0089] Preferably, the H-shaped hook head keeps the surface of the flat first element parallel to the second element in order to set the slot height.

[0090] Preferably, the gate bar slot is provided with widened lips that diverge in the flow direction.

[0091] According to another aspect of the present invention, there is provided a foaming or frothing system that includes the above-described variable slot gate bar and a control system.

[0092] Thus, advantageously, there is provided a system that can automatically respond to pressure changes inside the gate bar, thereby providing a discharge flow under perfect operating conditions.

[0093] The response and adaptation of the slot height to the flow rate and pressure changes may be related to the pressure balance between the control system operating under pressure and the pressure of the reaction fluid within the elements constituting the gate rod, or to the translation or rotation of the system controlling the opening of the gate or slot.

[0094] According to a preferred embodiment, the control system includes a proportional valve controlled by a programmable logic controller.

[0095] Thus, advantageously, the system simply controls the pressure in the gate rod passage by pressure setting, so the gate continuously moves only according to the pressure balance between the control device and the gate rod passage.

[0096] The pressure at the control device is set by the proportional valve, which is controlled by a programmable logic controller or other type of device controller.

[0097] According to an alternative embodiment, the control system includes an I-to-P (current-pressure) control function that is closed-loop with at least one pressure sensor applied to the gate rod passage.

[0098] Advantageously, this alternative embodiment of the system is still characterized by controlling the pressure in the gate rod passage by pressure setting, so the gate rod continuously moves according to a closed-loop control that regulates the pressure in the gate rod passage, reads this pressure, and modifies the control pressure at the command device.

[0099] The pressure at the command device is set by the proportional valve, which is controlled by a programmable logic controller or other type of device controller within the closed loop and is feedback by the pressure sensor within the gate rod.

[0100] According to an alternative embodiment, the control system includes a controller and a regulator that are closed-loop with a position sensor mounted on the variable slot gate rod or on the command device board.

[0101] Advantageously, according to the first variant, this alternative embodiment of the system can first adjust only the slot height according to a set of positions set by the operator. In this case, there is a closed-loop control between the open position of the slot and the controller of each command device.

[0102] The proportional valve or the electrical control system adjusts the position of the slot to a set value.

[0103] Alternatively, according to the second variant, a second closed-loop controller can change the opening according to the pressure value within the gate rod. Thus, a second closed-loop controller superior to the position controller modifies the opening value according to the pressure value measured within the gate rod.

[0104] This control system is more complex but more stable and insensitive to friction and stick-slip problems.

[0105] This double - closed - loop system still controls the pressure at the gate - rod passage by controlling the gap at the slot and slowly modifies the gap according to the difference between the measured pressure and the set pressure.

[0106] The position of the command device is set by an electrical controller or a proportional valve on the motor.

[0107] The control function is implemented by a programmable logic controller or other types of device controllers in the two closed - loops. The inner closed - loop is fed back by the position of the actuator, and the higher - level closed - loop is fed back by a pressure sensor that reads the pressure inside the gate - rod.

[0108] The startup procedure can be to set the opening value when the system can control the gate position, or to open the gate with a gap of, for example, 3 mm and start conveying the reaction mixture.

[0109] When the pressure is full, start the open - loop or closed - loop pressure control.

[0110] The features and advantages of the present invention will be disclosed with reference to the drawings relating to illustrative and non - restrictive embodiments. Description of the Drawings

[0111] Figure 1 is a cross - sectional view of a gate - rod according to the prior art;

[0112] Figure 2 is a schematic cross - sectional view of a gate - rod according to an embodiment of the present invention;

[0113] Figure 3 is Figure 2 a schematic plan view of an embodiment of the gate - rod of

[0114] Figure 4 is a cross - sectional view of an alternative embodiment of a gate - rod according to an embodiment of the present invention;

[0115] Figure 5 is a cross - sectional view of an alternative embodiment of a gate - rod according to an embodiment of the present invention;

[0116] Figure 6A and Figure 6B are cross - sectional views of two variants of an alternative embodiment of a gate - rod according to an embodiment of the present invention;

[0117] Figure 7 is a cross - sectional view of an alternative embodiment of a gate - rod according to an embodiment of the present invention;

[0118] Figure 8 is a cross - sectional view of an alternative embodiment of a gate - rod according to an embodiment of the present invention;

[0119] Figure 9Cross-sectional view of an alternative embodiment of a gate bar according to an embodiment of the present invention;

[0120] Figure 10 Schematic cross-sectional front view of an alternative embodiment of a gate bar according to an embodiment of the present invention;

[0121] Figure 11 is Figure 10 Lateral cross-sectional view of the gate bar of.

[0122] In different figures, similar elements will be identified by similar reference numerals. Detailed Description

[0123] Figure 1 Shows a cross-sectional view of a gate bar 1000 according to the prior art.

[0124] The gate bar 1000 is composed of two bars (usually steel), and the top inlet is located in the middle of the bar length, as Figure 3 shown.

[0125] The first bar 1001 is usually substantially flat, and the second bar 1002 is usually U-shaped, defining a gate bar distribution channel 1003 passing through the centers of the two bars 1001, 1002, that is, a pressure equalization and flow distribution chamber.

[0126] The gate bar 1000 further includes an outlet groove 1004 for distributing the liquid polyurethane mixture over the casting area of the slab material production machine in the full production width.

[0127] The outlet groove 1004 is determined by calculation based on the pressure required for the solubility of CO 2 in a mixture of various other chemicals. The outlet groove 1004 is set using a combination of spacer gaskets 1005 made of flat metal sheets.

[0128] The spacer gasket 1005 can be composed of multiple layers to set the desired opening of the outlet groove 1004 at the front.

[0129] The two bars 1001, 1002 of the gate bar 1000 are tightly connected by bolts.

[0130] Figure 2 Shows a variable slot gate bar 100 according to a preferred embodiment of the present invention.

[0131] The variable slot gate bar 100 is a non-CO 2 gate bar with a pressurizing mechanism that typically has multiple positions along the length of the gate bar.

[0132] The variable slot gate rod 100 includes a flat first element 101 and a second element 102, and the second element 102 has at least one flow distribution channel 106 defined by a recess 103. In the present embodiment, the second element 102 is substantially U-shaped.

[0133] The flat first element 101 is movable towards the second element 102 guided by a connection and linkage device 105, and the connection and linkage device 105 includes a series of pins 105B that slide in corresponding guiding cylindrical holes 105A and are pressed by air pressure acting on a series of pistons 117. The flat first element 101 and the second element 102 are connected by means of an inverted C-shaped structure formed by connections at the rear surfaces of two holding brackets 107. This connection is achieved by fixing bolts 108.

[0134] Therefore, the flat first element 101 and the second element 102 define an inner gate rod flow distribution channel 106 at the flow recess 103 of the second element 102.

[0135] Each of the holding brackets 107 has a first side and a second side. The first side abuts on the surfaces of the flat first element 101 and the second element 102 opposite to the gate rod channel 106, and the second side is perpendicular to the first side and at least partially overlaps with the first side of another holding bracket to allow them to be fixed by bolts 108.

[0136] The force determined by the sum of the forces caused by the air pressure in the cylindrical chamber 116 is balanced by the force acting on the element 101 by the pressure of the resin in the distribution channel. The flat first element 101 and the second element 102 are spaced apart from each other by the balance of forces.

[0137] The pressure in the distribution chamber is determined by the flow rate multiplied by the value of the hydraulic restriction caused by the clearance or height of the slot 110.

[0138] Since the restriction decreases as the clearance widens or increases, when the above forces are in balance, the movement of the element 101 stops, thereby defining the height of the gate slot 110 through the clearance towards the front surface.

[0139] In the illustrated embodiment, the gate slot 110 is provided with widened lips 111 that diverge in the flow direction.

[0140] According to the previous application EP0734830A2 of the same applicant, in order to obtain good laminar flow conditions and thus avoid critical turbulent conditions in the mixture discharged from the gate slot 110, it is advantageous to maintain a very small divergence angle of the side surface of the gate slot 110.

[0141] Preferably, the gate rod slot 110 has an initial portion with a relatively small height, which is defined by parallel planar walls, followed by a diverging widened lip 111. The ratio between the dimensions and lengths of the two parallel and diverging portions of the gate rod slot 110 can vary depending on the circumstances, and generally the diverging widened lip 111 can be restricted to the end of the outlet edge of the gate rod slot 110.

[0142] Therefore, the variable slot gate rod 100 is adapted to release the discharge flow of the chemical reaction mixture through the gate rod slot 110.

[0143] According to the present invention, the height of the gate rod slot 110 can be automatically adjusted to control the pressure of the discharge flow.

[0144] In this embodiment, a ramp-shaped guiding element 112 is further provided at the end of the widened lip 111 so as to guide the discharge flow.

[0145] The guiding element 112 is connected to the side of the second element 102 through a connecting bolt 113 and a bushing element 114.

[0146] The flexible seal 115 placed in the groove provided in the second element 102 along the longitudinal and lateral boundaries prevents the liquid reactive polyurethane from infiltrating into the space behind the gate rod flow distribution channel 106 and along both sides of the second element 102.

[0147] In Figure 2 and Figure 3 In the present embodiment of the variable slot gate rod 100 shown, the adjustment of the height or clearance of the gate rod slot 110 is performed by a pressurized stroke cylinder 116 having a corresponding piston 117, preferably a plurality of pressurized stroke cylinders 116 having a plurality of corresponding pistons 117, which are longitudinally spaced apart along the flat first element 101 and are adapted to move the flat first element 101 relative to the second element 102 upward and downward.

[0148] In other words, the flat first element 101 of the variable slot gate rod 100 can move upward and downward by means of a sliding cylindrical surface that matches a series of pins.

[0149] A possible start-up procedure can be, for example, to open the gate rod slot 110 to a maximum displacement of 3 mm and start production.

[0150] Figure 3 Shows a view of a variant of the gate rod of a 2-meter pressurizing mechanism that is non-CO 2 The pressurizing mechanism has a plurality of pressurized stroke cylinders 116, and the plurality of pressurized stroke cylinders 116 have a plurality of corresponding pistons 117.

[0151] Figure 4An alternative embodiment of the present invention is shown, in which a variable sluice gate lever 200 is provided, which also includes a blade support pitch hinge 201 to allow rotation and movement of the flat first element 101 relative to the second element 102, thereby adjusting the clearance of the gate lever slot 110.

[0152] The blade support pitch hinge is located on the rear part 202 between the flat first element 101 and the second element 102.

[0153] Thus, the flat first element 101 of the variable sluice gate lever 200 can pitch up and down in a manner articulated against the blade support hinge 201.

[0154] This type of articulation has no frictional effect.

[0155] At least one pressure stroke cylinder 216 having a corresponding piston 217, preferably a plurality of pressure stroke cylinders 216 having a plurality of corresponding pistons 217, in the second element 102 preferably located at the blade support hinge 201, can be controlled by air pressure or liquid pressure and serves to balance forces and control the pressure within the variable sluice gate lever 200.

[0156] In addition, the variable sluice gate lever 200 includes a conical spring system 203 as a connecting or linkage device, which has a conical spring 203A, or a stack of conical springs 203A, and has a fastening screw 203B for applying a load preload to overcome the force synthesis caused by the pressure in the gate lever channel 106 plus the force of at least one piston controlling the closing of the variable sluice gate lever 200.

[0157] Thus, contact with the blade support hinge 201 is maintained.

[0158] The conical spring fastening screw 203B is inserted through the flat first element 101 with an appropriate clearance and the corresponding seat 218 implemented in the second element 102.

[0159] In addition, the variable sluice gate lever 200 includes a ball transfer bearing bracket 204 located between the piston 217 and the flat first element 101.

[0160] Thus, contact and force transmission between the piston 217 and the flat first element 101 are maintained in the case of involving friction.

[0161] Alternatively, a circular ball bearing can be used.

[0162] Also in this embodiment, flexible seals prevent liquid reactive polyurethane from infiltrating into the space behind the gate lever channel 106 and along the two sides of the second element 102.

[0163] Figure 5 Another alternative embodiment of the present invention is shown, in which a variable slot gate lever 300 is provided.

[0164] The variable slot gate lever 300 provides a second element 302, which includes a flow recess 303 for flow distribution and a control recess 304 located on the rear portion 305 of the second element 302.

[0165] The variable slot gate lever 300 further includes a flexible bladder 306, which is located in the control recess 304, between the flat first element 101 and the second element 302, is controlled by air pressure or liquid pressure, and is adapted to create a force balance and control of the pressure within the variable slot gate lever 300.

[0166] Also in this case, a conical spring 203A or a stack of conical springs 203A and a fastening screw 203B for applying a load preload are provided to overcome the force synthesis caused by the pressure in the gate lever distribution channel 106 plus the force of the flexible bladder 306 that controls the closing of the variable slot gate lever 300.

[0167] The flexible bladder 306 is inflated through a tube connector 307 inserted into the bottom of the flexible bladder 306.

[0168] Also in this embodiment, a flexible seal prevents liquid reactive polyurethane from penetrating into the space located behind the gate lever channel 106, between the channel and the screw 203B, and along the two side edges of the second element 302.

[0169] Also in this embodiment, the flat first element 101 of the variable slot gate lever 300 can pitch up and down in a manner hinged against a similar blade support hinge 201 (not shown).

[0170] Figure 6A A first variant of an alternative embodiment of the present invention is shown, in which a variable slot gate lever 400 is provided.

[0171] The variable slot gate lever 400 provides a flat first element 401, which consists of two longitudinal parts, namely a front part 401A and a rear part 401B, and the two longitudinal parts are connected by a flexible Z-shaped joint 402 (as a connecting device).

[0172] The Z-shaped joint 402 forms an elastic and gapless hinge in the shape of an elastic fork element along the entire longitudinal dimension of the flat first element 401.

[0173] The front part 401A can pitch up due to the flexibility of the "Z" - shaped joint 402.

[0174] Alternatively, according toFigure 6B In the second variant example shown, a C-shaped joint 402B can be used.

[0175] The rear part 401B is fixed to the second element 102 by a series of screws at the rear threaded part 403, and the initial value of the gate lever groove 110 is fixed by a spacer 404 located below the threaded part 403.

[0176] The Z-shaped joint 402 forms an elastic and gapless hinge with an elastic fork element along the entire longitudinal dimension of the variable groove gate lever 400.

[0177] The flat flexible metal tube 405 is pressed into the front groove 406 of the Z-shaped joint 402.

[0178] When the tube 405 is supplied with hydraulic pressure, it can expand and transfer part of the pressure to the wall of the groove 406, and this force can counteract the pressure in the flow distribution channel 106 and can also close the gate lever groove 110.

[0179] An appropriate spacer 404 can set the initial clearance of the conveying groove 110.

[0180] A position sensor can be fixed on the permanent surface of the element 401 to read the distance change on both sides of the groove and allow the application of position control to better stabilize the pressure control of the gate lever. The reciprocating motion can be amplified by applying a lever to support the position sensor.

[0181] Also in this embodiment, a flexible seal prevents liquid reactive polyurethane from infiltrating into the space behind the gate lever groove 106 and along the two side edges of the second element 101.

[0182] Figure 7 Another alternative embodiment of the present invention is shown, in which a variable groove gate lever 500 is provided.

[0183] In the variable groove gate lever 500, the flat first element 101 and the second element 102 are connected by at least one hinge 501 or a series of hinges 501 at the rear part 502.

[0184] The hinge 501 is connected and operable by a motor 503 and a gearbox, and the gearbox is provided with a gapless solution.

[0185] Therefore, the variable groove gate lever 500 rotates the element 101 directly connected to the hinge 501 and adjusts the height of the gate lever groove 110 up or down according to the clearance between the first element 101 and the second element 102, causing the motor-controlled hinge 501 to rotate, which is located between them, depending on the pressure measured in the gate lever channel 106.

[0186] In the case of a series of hinges 501, all the hinges are well aligned by means of a tool, and two parts of a common axis 504 as a connecting device are used to control the rotation of the flat first element 101 during operation.

[0187] Also in this embodiment, a flexible seal prevents liquid reactive polyurethane from penetrating into the space located behind the gate bar groove 106 and along the two side edges of the second element 102.

[0188] A position sensor can be applied to the rotating motor or hinge rotation to read and measure the clearance of the gate bar groove, thereby exerting position control over the clearance.

[0189] Figure 8 Another alternative embodiment of the present invention is shown, in which a variable slot gate bar 600 is provided.

[0190] In the variable slot gate bar 600, the flat first element 101 and the second element 102 are connected by a hinge 601 or a series of hinges 601 located at the rear part 602.

[0191] The variable slot gate bar 600 further includes a hydraulically controlled piston 606, which is connected by a corresponding rotatable connection between a support extension 603 located at the rear part of the variable slot gate bar 600 and a front extension 604 of the flat first element 101 at an angle through the hinge.

[0192] Therefore, by the action of the hydraulically controlled piston 606, the flat first element 101 is adapted to rotate around the hinge 601, thereby adjusting the height of the gate bar groove 110 according to the pressure measured within the gate bar channel 106.

[0193] In the case of a series of hinges 601, all the hinges are well aligned by means of a tool, and a common axis 605 as a connecting device is used to control the rotation of the flat first element 101 during operation.

[0194] A position sensor can be applied to the cylinder movement or hinge rotation to read and measure the clearance of the gate bar groove and exert position control over the clearance.

[0195] Also in this embodiment, a flexible seal prevents liquid reactive polyurethane from penetrating into the space located behind the gate bar groove 106 and along the two side edges of the second element 102.

[0196] Figure 9 Another alternative embodiment of the present invention is shown, in which a variable slot gate bar 700 is provided.

[0197] The variable slot gate bar 700 is very similar to the variable slot gate bar 600 of the previous embodiment.

[0198] The variable slot gate bar 700 further includes a lever mechanism 701 which is connected to the flat first element 101 and the hinge 601, and the hinge 601 is adapted to control the rotation of the flat first element 101 and allow more precise control of the gate bar slot 110.

[0199] Alternatively, in addition to the hydraulically controlled piston 606 of the previous embodiment, one or more pneumatic cylinders (not shown) may be used and the air pressure may be directly controlled according to the pressure within the gate bar channel 106.

[0200] Also in this embodiment, the flexible seal prevents the liquid reactive polyurethane from infiltrating into the space located behind the gate bar distribution channel 106 and along the two side edges of the second element 102.

[0201] Figure 10 and Figure 11 Another alternative embodiment of the present invention is shown, in which a variable slot gate bar 800 is provided.

[0202] The variable slot gate bar 800 includes a hydraulically controlled piston 801 and a sliding hook 802 (as a connecting device) connected thereto, and the sliding hook 802 includes a plurality of inclined surfaces 803 that slide against corresponding inclined lifting surfaces 804.

[0203] Therefore, this solution provides a vertical linear movement of the flat first element 101 through the sliding hook 802, wherein the sliding of the inclined surface 803 actuated by the hydraulically controlled piston 801 against the inclined lifting surface 804 controls the opening and closing of the gate bar slot 110 according to the pressure measured within the gate bar slot 106 and the difference between the set pressure and the measured pressure in the gate bar channel 106.

[0204] The sliding hook 802 has an H-shaped cross-section to allow opening or closing according to the movement of the sliding member.

[0205] In Figure 11 It can be seen that the fixed pin 805 docking with the transverse slot 806 extending in the vertical direction moves the flat first element 101 up and down in the opposite direction of its translation.

[0206] The H-shaped sliding hook 802 keeps the surface of the flat first element 101 parallel to the second element 102.

[0207] Also in this embodiment, the flexible seal prevents the liquid reactive polyurethane from infiltrating into the space located behind the gate bar channel 106 and along the two side edges of the second element 102.

[0208] Also for this embodiment, a position sensor may be applied to the cylinder movement or sliding translation to read and measure the gap of the gate bar slot and apply position control to the gap.

[0209] According to the present invention, the disclosed variable slot gate bar is functionally coupled to a control system in a foaming system or a foaming system to measure the pressure within the gate bar channel 106 and respond with a correctly adjusted width of the gate bar slots 110 and a correct discharge flow rate.

[0210] The pressure within the gate bar channel 106 depends on the chemical mixture flowing outside the gate bar slots 110.

[0211] The pressurization system is based on the control of the chemical mixture flowing through the variable slot gate bar, and this pressure naturally generates a force within the gate bar that can be used to open the gate bar slots 110.

[0212] The control system sets a preselected desired pressure according to the foam formulation.

[0213] As described above, one possible startup procedure could be to open the gate bar slots 110 to a maximum displacement of 3 mm and start production.

[0214] An alternative startup sequence is to provide the control software with a matrix containing different flow rates, formulations, gas additions, viscosities, and the corresponding openings of the gate bar slots 110, and the software checks the new values of the formulation, performs linear interpolation within the set values, and pre-sets the openings of the gate bar slots 110 before starting the flow delivery.

[0215] Then pressure is applied to the top of the variable slot gate bar until the desired set pressure is reached.

[0216] Then, the control system achieves closed-loop pressure control by slowly increasing the control gain.

[0217] When the closed-loop is fully enabled, the control system continuously monitors, regulates, and controls the gate bar pressure.

[0218] Taking the two-meter-wide variable slot gate bar using multiple pressurization stroke cylinders in the first embodiment disclosed above as a reference example, a sample of the pressurization calculation can be provided.

[0219] Due to the required vertical movement, the forces to be calculated are the top and bottom surfaces of the gate bar distribution channel 106.

[0220] Channel width W c = 70 mm

[0221] Channel length L c = 2000 mm

[0222] The area of one channel surface = S c = W c * L c = 140000 mm 2

[0223] The actual pressure inside the gate rod needs to be between 0.2 bar and 1 bar, i.e., between 0.02 N / mm 2 (minimum pressure) and 0.1 N / mm 2 (maximum pressure).

[0224] Therefore:

[0225] The minimum force applied to the gate rod on the vertical axis = 0.02 N / mm 2 *Sc = 0.02S c

[0226] The maximum force applied to the gate rod on the vertical axis = 0.1 N / mm 2 *Sc = 0.1S c

[0227] 0.02S c = 140000 * 0.02 = 2800 N

[0228] 0.1S c = 140000 * 0.1 = 14000 N

[0229] Calculate the required area using the pressurizing stroke cylinder, assuming the maximum working pressure of the pressurizing stroke cylinder is 5 bar, i.e., 0.5 N / mm 2 .

[0230] The total area of the pressurizing stroke cylinder = Tsp = 0.1S c / 0.5 = 28000 mm 2

[0231] It is also assumed that a single pressurizing stroke cylinder can have a diameter between 30 mm (D min ) and 80 mm (D max ).

[0232] S pmin = D min 2 * 3.14 / 4

[0233] S pmax = D max 2 * 3.14 / 4

[0234] The number of pressurizing stroke cylinders depends on its diameter and should be:

[0235] 0.2 * Sc / S pmin

[0236] 0.2 * Sc / S pmax

[0237] Assuming the diameter of the pressurizing stroke cylinder is 40 mm, the number of pressurizing stroke cylinders is:

[0238]

[0239] Round to 24 pressurization stroke cylinders.

[0240] As described above, this is just a calculation based on exemplary assumptions and exemplary embodiments to explain how the control system of the foaming or frothing system according to the present invention works.

[0241] Depending on the need and depending on the accidental preferences according to different embodiments, the present invention provides four embodiments of a control system operably coupled to a variable sluice gate rod.

[0242] According to the first embodiment, a control system for the internal pressure of the gate rod distribution channel 106 is provided, which is adapted to control the pressure at the gate rod channel 106 by setting the pressure to a pressurization stroke cylinder or a bladder or a flat flexible metal tube or a pneumatic or hydraulic cylinder according to the type of the variable sluice gate rod.

[0243] Therefore, the width of the gate rod slot 110 continuously varies only according to the pressure balance between the control device and the gate rod channel 106.

[0244] The pressure at the control device is set by a proportional valve, which is controlled by a programmable logic controller or other types of device controllers.

[0245] Interferences introduced by friction of the piston and sliding components such as pins during movement can be eliminated by applying flutter to the flat first element.

[0246] According to the second embodiment, a control system with a closed-loop I-to-P control function is provided, which has a flushing separation diaphragm pressure sensor applied to the gate rod channel 106, and the pressure sensor is adapted to control the pressure at the gate rod channel 106 by setting the pressure to a pressurization stroke cylinder or a bladder or a flat flexible metal tube or a pneumatic or hydraulic cylinder according to the type of the variable sluice gate rod.

[0247] Therefore, the width of the gate rod slot 110 continuously varies according to the closed-loop control, which regulates the pressure in the gate rod channel 106, reads the pressure and modifies the control pressure at the command device.

[0248] The pressure at the command device is set by a proportional valve, which is controlled by a programmable logic controller or other types of device controllers and is feedback by a pressure sensor in the gate rod.

[0249] According to the third and fourth embodiments, a pressure control system in the gate rod channel 106 is provided, which sets the precise opening of the gate rod slot 110 in a closed-loop manner through a position sensor installed on the variable sluice gate rod or on the command and control device board.

[0250] According to the third embodiment, the control system first adjusts the gate rod slot 110 only according to a set of positions set by the operator. In this case, there is a closed-loop controller between the position of the gate rod slot 110, which is usually the opening, and the controller of each actuating device with a position sensor, so as to adjust only the position of the actuator.

[0251] The proportional valve or the electric control system adjusts the position of the gate rod slot to a set value.

[0252] According to the fourth embodiment, the control system provides a second closed-loop controller, which changes the opening according to the pressure value in the variable slot gate rod. The second closed-loop control superior to the position control sets a new opening value according to the pressure value measured in the distribution channel or at the inlet of the distribution channel of the variable slot gate rod.

[0253] This control system is more complex but more stable and insensitive to friction and stick-slip problems.

[0254] This double closed-loop system still controls the pressure of the gate rod channel 106 by controlling the gap at the gate rod slot 110, and slowly modifies its gap according to the difference between the measured pressure and the set pressure.

[0255] For example, using the variable slot gate rod 600, the control system opens or closes the gate rod slot 110 in the closed-loop of the piston position control according to the difference between the set pressure and the measured pressure.

[0256] Differently, using the variable slot gate rod 500, the control system opens or closes the gate rod slot 110 in the closed-loop of the rotation control, for example, positioning the flat first element 101 by means of an encoder connected to the rotating shaft. Another closed-loop controller opens or closes the gate rod slot 110 according to the difference between the set pressure and the measured pressure.

[0257] The positions of the actuator and the command device are set by the electric controller or the proportional valve on the motor.

[0258] The control function is realized by a programmable logic controller or other types of system controllers through two closed-loops. One internal closed-loop is fed back by the position of the actuator, and the other advanced closed-loop is fed back by the pressure sensor that reads the resin pressure inside the variable slot gate rod or at the inlet of the distribution channel of the variable slot gate rod.

[0259] The startup program can be to set the value of the opening when the system can control the gate position, or to open the gate with a 3-mm gap on the mechanical stop device and start conveying the reactive mixture.

[0260] When the pressure is full, there is usually a time delay, which starts the open-loop or closed-loop pressure control.

[0261] Advantageously, the present invention allows automatic and precise control of the discharge flow from the gate rod.

[0262] More advantageously, the present invention provides embodiments suitable for implementation in existing foaming or bubbling systems, and certain components can still continue to be used.

[0263] In addition, the present invention is not limited by continuous manual intervention.

[0264] Finally, advantageously, the present invention does not require complex maintenance procedures.

[0265] Those skilled in the art will understand that the embodiments can be subject to various changes and modifications according to specific and contingent needs, all of which are included within the scope of protection of the present invention as defined by the following claims.

Claims

1. A variable slot gate lever (100, 200, 300, 400, 500, 600, 700, 800) for a foaming or bubbling system, comprising: a flat first element (101, 401) and a second element (102, 202, 302), the second element (102, 202, 302) having at least one flow recess (103, 303); the flat first element (101, 401) and the second element (102, 202, 302) are connected at a rear surface (104) of the second element (102, 202, 302) by at least one connecting device (105, 203, 402, 504, 605, 802), the flat first element (101, 401) and the second element (102, 202, 302) are spaced apart from each other by a gap that faces a front surface (109) of the second element (102, 202, 302) and defines a gate lever slot (110), wherein the flat first element (101, 401) and the second element (102, 202, 302) define an internal gate lever flow distribution channel (106) at the flow recess (103, 303) of the second element (102, 202, 302), the variable slot gate lever (100, 200, 300, 400, 500, 600, 700, 800) is adapted to release an output flow of a chemically reactive mixture through the gate lever slot (110), characterized in that a height of the gate lever slot (110) is automatically adjustable to control a pressure of the output flow at the distribution channel (106).

2. The variable slot gate lever (100, 200, 600, 700) according to claim 1, further comprising at least one pressurized stroke cylinder (116, 216, 606) having a respective piston (117, 217), the piston (117, 217) being adapted to move or rotate the flat first element (101, 401) relative to the second element (102, 202, 302) up and down or in rotation along a hinge device, thereby adjusting the height of the gate lever slot (110).

3. The variable slot gate lever (200, 300) according to claim 1, further comprising a blade support hinge (201) to allow the flat first element (101) to pitch and rotate relative to the second element (202, 302), thereby adjusting the height of the gate lever slot (110).

4. The variable slot gate lever (200, 300) according to claim 3, further comprising at least one conical spring system (203), the conical spring system having a conical spring (203A) or a stack of conical springs, and having a fastening screw (203B) with a load-applying preload.

5. The variable slot gate bar (200) according to claim 4 further comprises at least one ball transfer bearing bracket (204) or at least one circular ball bearing for transmitting pitching force between at least one piston (217) and the flat first element (101) of the variable slot gate bar (200).

6. The variable slot gate bar (300) according to claim 4, wherein, the second element (302) includes a setting and control recess (304) for a control element and further includes: a flexible bladder (306) located in the setting and control recess (304) between the flat first element (101) and the second element (302), controlled by air pressure or liquid pressure and adapted to create a force balance and control of the pressure within the flow distribution channel (106) of the variable slot gate bar (300).

7. The variable slot gate bar (400) according to claim 1 further comprises: a Z-shaped joint (402) or a C-shaped joint (402B) that forms an elastic and gapless pitching hinge in the shape of an elastic fork element along the entire longitudinal dimension of the flat first element (401); and a flat metal tube (405) pressed into the front recess (406) of the elastic and gapless hinge, the flat metal tube typically being provided with a connection to a hydraulic source.

8. The variable slot gate bar (500) according to claim 1 further comprises a motor-controlled hinge (501) for moving the flat first element (101) up and down relative to the second element (102) to adjust the height of the gate bar slot (110).

9. The variable slot gate bar (600) according to claim 1 further comprises a hydraulically controlled piston (606) and at least one hinge (601) located between an extension of the flat first element (101) and the second element (102), wherein, the flat first element (101) is adapted to rotate about the hinge (601) under the action of the hydraulically controlled piston (606).

10. The variable slot gate bar (700) according to claim 9 further comprises a lever mechanism (701) connected to the flat first element (101) and an extension of the second element connected by the hinge (601), adapted to control the rotation of the flat first element (101) and allow for more precise control of the gate bar slot (110).

11. The variable slot gate bar (800) according to claim 1 further comprises a hydraulically controlled piston (801) and a sliding hook head (802) connected to the hydraulically controlled piston (801), the sliding hook head (802) including a plurality of inclined surfaces (803) that slide against corresponding inclined lifting surfaces (804).

12. The variable slot gate bar (100, 200, 300, 400, 500, 600, 700, 800) according to any one of the preceding claims 1 to 11, wherein, the gate bar slot (110) is provided with a widened lip (111) diverging in the flow direction.

13. A foaming or frothing system comprising the variable slot gate bar (100, 200, 300, 400, 500, 600, 700, 800) according to any one of the preceding claims 1 to 12 and a control system.

14. The foaming or frothing system according to claim 13, wherein, the control system comprises a proportional valve controlled by a programmable logic controller.

15. The foaming or frothing system according to claim 13, wherein, the control system comprises an I-to-P control function which is closed-loop with at least one pressure sensor, and the pressure sensor is applied to the gate bar distribution channel or the supply of the gate bar distribution channel.

16. The foaming or frothing system according to claim 13, wherein, the control system comprises a controller and a regulator which are closed-loop with a position sensor mounted on the variable slot gate bar or on the command and control device board.

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