Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
  • B07B1/12—Apparatus having only parallel elements
  • B07B1/14—Roller screens
  • B07B1/15—Roller screens using corrugated, grooved or ribbed rollers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
  • B27N3/08—Moulding or pressing
  • B27N3/10—Moulding of mats
  • B27N3/14—Distributing or orienting the particles or fibres

Definitions

• the present invention concerns machines for selecting woody material which is then used to obtain chipboard panels, for example panels such as “Particleboards” and OSB (Oriented Strand Boards), and in particular concerns the selector rollers used in them.
• panels such as “Particleboards” and OSB (Oriented Strand Boards)
• OSB Oriented Strand Boards
• MDF Medium Density Fiberboard
• chipboard panels we mean those panels made of wood chips of medium, fine and very fine size, bonded with suitable glues.
• the panels are normally characterized by a multilayer structure or by a structure which is defined as having a“continuously variable particle size”.
• the chips are selected either at constant size, or at variable size.
• OSB panels are formed by of three layers, respectively consisting of large fibers, in the specific field also defined as“strands”, or “wafers” suitably oriented in the external layers, and of small fibers, or“strands” with the addition of chips of the type used in chipboard panels, also suitably oriented, in the central layer.
• the strands and the chips are bonded with suitable glues.
• the mass of chips for the former, and of strands plus chips for the latter, in any desired stratification is then used to generate a chip mattress.
• the mattress is then subjected to hot pressing in continuous processes to obtain the panels in the desired formulation.
• a panel thus obtained exits the press with a very low humidity, in the order of 5 - 6%, or less.
• the panels After a certain period of this process of absorbing ambient humidity, the panels reach a condition of equilibrium which, in normal climates, stands at a humidity of around 9-15%.
• the increase in humidity from 5-6% to 9-15% is absorbed and retained by the wood particles (the chips or strands) that make up the panel.
• the panel increases in volume without modifying its flatness.
• the chips which do not have a reduced thickness while accumulating almost the same unitary volume of water as the remaining chips, due to their cube-shaped and/or thick conformation, swell more than the thin chips, which also enjoy greater specific insulation because of the glue, generating areas or points of swelling located in the panel, and consequently in the piece of furniture of which the panel is part.
• the chips are screened into suitable particle sizes, each of which is pneumatically selected to remove the cubic and/or thick particles in order to have a reasonable certainty that the so-called anomalous chips are not present in the panel.
• This process is carried out in a dry condition, and ends with the refining of the cubic or thick particles previously removed from the mass.
• the solution to the problem is to remove the cubic and/or thick particles in a humid condition, to be able to refine them with the minimum generation of dust.
• Applicant has therefore set himself the task of studying in depth the phenomenon of simplifying and better guaranteeing the quality of the selection so as to obtain a considerable reduction in costs, and at the same time a guaranteed exclusion of the chips with undesired geometric characteristics.
• EP-B- 1007227 proposes selection screens in which there are selector rollers having a cusp conformation with reciprocal cooperation (see figs la and lb) in which, opposite to steps of a certain height there are steps of a lower height.
• the steps of a certain height cooperate with the steps of a lower height that may or may not have circumferential discontinuity. This generates free areas that allow the transit of chips having unsuitable sizes.
• the known selector roller 110 has a hole (not shown) so that it can be keyed on a roller bearing shaft.
• the roller 110 has circumferential cusps 111 so that a plurality of rollers 110 (fig. la) can be faced and positioned on parallel shafts 12, in staggered order.
• the circumferential cusps 111 have a plurality of steps 113 (fig. lb) which develop along the circumference of the roller 110, and which alternately have different heights.
• Each step 113 has a surface working defined by recesses 114 staggered with respect to each other along the circumferential development of two adjacent steps 113 of the roller 110.
• the recesses 114 are made on a plane orthogonal to a plane of each step 113, so that along the circumference of each step 113 empty spaces 115 are created.
• rollers 110 have the disadvantage that, due to the different heights of the vertices 118 of the staggered steps 113, when two rollers 110 are disposed facing each other, interspaces 116 are formed between the respective cusps 111 which do not allow an accurate and precise selection of the chips.
• rollers according to the other proposal present in document EP-B- 1007227 (see fig. 2b), can have the walls of the cusps with pseudo-radial milling or upsetting.
• selector rollers 210 are shown in figs. 2a-2c, where the cusps 211 have radial millings or upsettings 214 which develop in a radial direction with respect to the central axis X of the roller 210, and affect the entire lateral surface of the cusp 211 itself.
• the radial millings 214 are possibly separated by circumferential furrows 215.
• the purpose of the present invention is to improve the high selection capability of any selection machine with rollers located on adjacent and parallel axes.
• the rollers operate separate and laterally displaced in relation to the rows of cooperating rollers located parallel.
• the purpose of the present invention is therefore to obtain selector rollers which, already in the humid processing step, guarantee the removal from the mass of chips of the cubic and/or thick particles, to prevent the selected material having to be recovered in the subsequent dry step, with an increase in costs due to the waste of raw material and energy.
• Another purpose is also to reduce investments, the energy consumption and the necessary labor, all of which entail a substantial reduction in costs and pollution.
• Another purpose is to make the selection of the chips in the humid step efficient, so as to prevent the formation of dust which can be harmful to the operators or the environment.
• the Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.
• the inventive idea which provides the basis for this significant technical progress is to provide improved selector rollers and to make them work differently from known selector rollers.
• the selector rollers are always cusp-shaped, so that the cusp of one roller cooperates with the opposite walls of the cusps of two adjacent rollers.
• the two sides of each cusp of a single selector roller, or more simply roller have a desired number of steps.
• the steps of a roller, in operation face the two faces of the two opposite rollers, which also have specular steps.
• the central portion of the roller also known as the upper bench, farthest from the axis of rotation of the roller, is conformed so as to face the throat which the two adjacent and opposite rollers create.
• the central portion is conformed so as to generate on the wood scale, or chips, both a drawing action and also a mechanical action of compression and flaking of the coarse particles passing through it.
• the central portion has a flat and smooth surface. According to variant embodiments, the central portion has a beveled surface along the circumferential sides.
• the central portion has a surface provided with millings and/or hollows and/or upsettings.
• the surface of the central portion has central depressions with, or without, circumferential interceptions.
• the circumferential central portion can have at least one circumferential groove.
• the circumferential groove develops in a spiral.
• the steps on the sides of the cusp are sufficient in number to be consistent with the type of chip and the action to be exerted thereon.
• the two sides of the cusp are specular.
• the two sides of the cusp have the same number of steps with different morphologies.
• Another variant is also possible which provides the two sides of the cusp with a different number of steps, which thus entails the need for a correct correlation between the rollers positioned on one shaft and the rollers positioned on the neighboring and parallel shafts.
• One roller must have a size correlated to the interaxis between two rows of rollers except for a value that guarantees non-interference in any working condition.
• a pitch or interaxis between the rows of rollers of about 82- 86 mm brings the maximum diameter of the roll to around 98-102 mm.
• screens can also be constructed with smaller or larger interaxes between the rows of rollers, which therefore give smaller or larger maximum diameters of the rollers, compared with the approximate sizes indicated above.
• the tread of the steps will advantageously be substantially parallel to the axis, while the riser can advantageously be substantially orthogonal to the axis.
• the tread can have a positive or negative inclination with respect to the parallelism with the axis, which can even reach 25°-30°.
• the riser can have a positive or negative inclination with respect to the orthogonality to the axis of rotation, which can even reach 25°-30°.
• the steps all have the same characteristics.
• the steps have one or more differentiations.
• the tread of all the steps has the same width.
• At least one step has a tread with a different measurement.
• the riser of all the steps has the same measurement.
• At least one step has a different height.
• the leading edge of each step is at least partly affected by a milling which creates a circumferential furrow.
• milling is used, said term is generic, since the same effect can be obtained by rolling, or also by molding.
• the milling can also affect the entire step in a circumferential direction.
• transverse furrows are present along the perimeter profile of each step, at regular intervals along the circumferential development of the step.
• the transverse furrows are each made on a radial plane with respect to the axis of the roller.
• the transverse furrows are made in a helical pattern along the external surface.
• the transverse furrows of one row of steps at intervals with respect to the transverse furrows of the upper and lower row.
• the furrows of the steps are positioned to create a progressive development in the rows of the steps toward the central axis, or toward the cusp.
• each roller can be made from two semi-rollers which normally affect half the roller and, facing each other on the back, obtain the roller.
• the solution of providing two semi-rollers allows to characterize the two halves of the cusp in a differentiated manner, said differentiation can be deliberately modified with every change of wood and/or chip and/or other factor incident on the selection.
• rollers can also be made with the two parts that make up the cusp which are specialized in different ways.
• the part closest to the axis located in the sides of the roller also called the lower bench, is flat.
• the variants identified have the function on the one hand of maximizing the selective result according to the structure of the selection machine and the speed of feed, and on the other hand to make the rollers compatible with the presence of any vibrating motions.
• Another characteristic of the variants is to identify the need to improve the selective appearance due to the type of wood and/or the characteristics of the chips to be selected.
• Another characteristic of the variants is to attach any unsuitable chips and to flake or break them.
• - figs. 2a-2c show a second known model of a selector roller used in the state of the art
• - figs. 4a-4b show a possible roller with four steps according to embodiments of the present invention
• - fig. 5 shows a detailed view, partly in section, of a portion of the roller in figs. 4a-4b;
• - figs. 5a-5b show detailed views along the section line V-V of fig. 5;
• - fig. 6 shows a detailed view, partly in section, of a portion of two opposite rollers of fig. 4a.
• rollers 10 are shown by way of example in figs. 3 a to 6.
• the rollers 10 have an annular shape, which develops around a central axis X, defining the axis of rotation, and are provided with a central hole 20 through which the roller 10 can be keyed onto a shaft 12 disposed parallel to the central axis X.
• the rollers 10 according to the invention have a lateral surface with a cusp shape 11.
• the rollers 10 comprise a circumferential central portion 18, having an annular shape, which defines the tip of the cusp 11.
• the cusps 11 have a stepped development 13.
• rollers 10 according to the invention are shown with cusps 11 which, in this case, have five (figs. 3a-3b) and four (figs. 4a-4b) steps 13 per side.
• the steps 13 are defined by cylindrical surface portions with a gradually decreasing diameter, which are progressively disposed toward the outside from the circumferential central portion 18.
• the rollers 10 according to the invention have lateral shoulders 17 with an annular shape, which protrude from the lower step 13 of the cusp portion 11 in a direction parallel to the central axis of the roller 10.
• the lateral shoulders 17 can be smooth or they have grooves or incisions.
• a roller 10 can be obtained in a single body and with the two sides of the cusp 11 identical, that is, with the two sides of the cusp 11 differently specialized.
• a roller 10 can also be obtained with two facing semi- rollers and possibly joined together in relation to the circumferential central portion 18.
• each semi-roller will have a circumferential semi-portion having a width correlated to that of the circumferential central portion 18 of a roller 10 in a single body.
• the steps 13 of a cusp 11 can all be the same, or differentiated on one side with respect to the other.
• the steps 13 can also be differentiated on the same side.
• the steps 13 each have a tread 14, and a riser 15.
• the treads 14 and the risers 15 of the steps 13 of respective cusps 11 of facing rollers 10 respectively face each other in a close position and cooperate with each other to prevent the transit of chips having a cubic and/or thick shape, and to allow the transit of only chips of suitable shape.
• the treads 14 and the risers 15 of the respective steps 13 of one and the other roller 10 define interspaces 32 which are consistent with the sizes of the chips to be selected.
• the riser 15 of one step 13 of a cusp 11 is parallel and close to the riser 15 of the previous step 13 of the other cusp 11
• the tread 14 of one step 13 of a cusp 11 is parallel and close to the tread 14 of a following step 13 of the other cusp 11.
• all the treads 14 of the steps 13 on at least one side of the cusp 11 develop parallel to each other.
• all the risers 15 of the steps 13 on at least one side of the cusp 11 develop parallel to each other.
• the tread 14 and the riser 15 of each step 13 develop substantially orthogonal to each other.
• the tread 14 is substantially parallel to the central axis X, while the riser is substantially orthogonal to the central axis X.
• the tread 14 can have a positive or negative inclination with respect to the parallelism with the central axis X.
• the riser 15 can have a positive or negative inclination with respect to the orthogonality to the central axis X.
• the interaxes between the shafts 12 can be modified to adjust the distance between the respective treads 14 of the facing rollers 10, and thus modify the size of the interspaces 32 and therefore the thickness of the chips which can transit through them.
• the interaxis between the shafts 12 can be variable with a desired progression or fixed, that is, at predefined intervals.
• the interaxis between the shafts 12 can be variable with a progressively increasing or decreasing development, from the beginning toward the discharge of a screen of a selection machine.
• the variations of the interaxes can be manual or governed and can be performed manually or in assisted mode, or again in a controlled and possibly programmed manner.
• positioning means suitable to allow the reciprocal positioning of the shafts 12.
• the positioning means can be the manual type, or automated.
• the roller 10 comprises a circumferential furrow 33 in correspondence with at least part of the leading edge of one or each step 13.
• the roller 10 comprises a circumferential furrow 33 in correspondence with the whole leading edge of each step 13.
• the steps 13 have transverse furrows 21, made in a transverse direction in the tread 14 and respectively in the riser 15.
• the furrows 21 continue beyond the edge of the step defined by respective riser 15 and tread 14 with a curved shape.
• the curved shape of the furrow 21 advantageously has a radius of curvature substantially tangent to the tread 14 and to the riser 15 of the bordering steps 13.
• the curve has an outward facing concavity.
• the base of the furrow 21 is substantially linear.
• the base of the furrow 21 has a certain thickness, having a substantially rectangular shape in plan view.
• the transverse furrows 21 are associated with hollows 22 made in the thickness of the step 13.
• the hollows 22 have a flared shape with respect to the plane of the transverse furrow 21.
• the hollows 22 can define in the steps 13 inclined walls with an inclination comprised between about 30° and about 60°.
• the hollows 22 are symmetrical to each other with respect to the respective transverse furrow 21.
• the hollows 22 can have smooth walls (figs. 5a and 5b) or have surface workings (fig. 5c).
• the transverse furrows 21 are disposed radially with respect to the central axis X, so as to define, together with the associated hollows 22, a pyramidal or truncated- pyramidal morphology, in which all the vertexes, or minor bases 23, are disposed substantially on a conical lateral surface.
• each step 13 the pyramids or truncated-pyramids of each step 13 are disposed in succession along the same annular crown.
• the transverse furrows 21 of one row of steps 13 are separated by the transverse furrows 21 of the upper and lower row.
• the vertices 23 of each step 13 are all disposed on a common circumference defined by the intersection between the respective risers 15 and tread 14.
• the pyramidal working minimizes the blockages of wood particles or chips between the profiles of adjacent concurrent rollers 10, preventing mechanical blockages and limiting the power absorbed by the drive system of the rollers.
• each tread 14 is defined by a succession of triangular portions 24, disposed with the base toward the central axis X and the vertex 23 facing toward the outside (see figs. 3c and 3d).
• each riser 15 is also defined by a succession of triangular portions 25, disposed with the base toward the circumferential central portion 18, and the vertex 23 facing toward the outside (see figs. 3c and 3d).
• the transverse furrows 21 and the associated hollows 22 can be disposed in an oblique and/or helical direction with respect to the central axis X.
• the characteristics of the steps 13, that is to say, the transverse furrows 21 and the separated hollows 22, can be obtained by milling, rolling, or molding.
• the transverse furrows 21 and the hollows 22 can be made with a circular cutter, also automatically.
• the circular cutter (not shown) can have a shaped profile even if the representation in fig. 5 identifies, by way of example only, the hollows 22 with identical walls.
• the circumferential central portion 18 can have a flat external surface.
• the circumferential central portion 18 can have grooves 26 disposed on the external surface, disposed at intervals along the circumference, which can have the most suitable shaping and conformation on each occasion.
• the grooves 26 can be parallel to the central axis X.
• the circumferential central portion 18 has an extemal surface defined by a succession of pyramidal or truncated pyramidal portions 29, defined by the grooves 26, with respective vertices, or minor bases, disposed substantially along the same circumference passing through the center line of the circumferential central portion 18.
• the grooves 26 are made with a helical or oblique development with respect to the central axis X.
• the external surface of the circumferential central portion 18 has upsettings, millings, or other workings.
• the circumferential central portion 18 has a central segment 27, on which the grooves 26 or other workings can be made, and lateral bevels 28.
• the bevels 28 can be flat or have specialized hollows.
• Both the circumferential central portion 18 and the lateral shoulders 17 can have specialized shapes in the case of particular needs, or specific chips.
• grooves 26 and/or the bevels 28 of the circumferential central portion 18 can be made by milling, rolling, or molding.
• the roller 10 can have an external diameter comprised between about 90 and 105 mm, and a thickness comprised between about 30 and 40 mm.
• the central hole 20 can have a diameter comprised between about 50 and 60 mm, although this size can vary according to the length of the shaft 12 and the total number of rollers 10 to be positioned adjacent.

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Citations (3)

• 2018
  • 2018-01-10 IT IT201800000688A patent/IT201800000688A1/it unknown
• 2019
  • 2019-01-09 EP EP19702527.3A patent/EP3737508B1/en active Active
  • 2019-01-09 PL PL19702527.3T patent/PL3737508T3/pl unknown
  • 2019-01-09 WO PCT/EP2019/025009 patent/WO2019137830A1/en unknown
  • 2019-01-09 ES ES19702527T patent/ES2926325T3/es active Active

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