Classifications

• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
  • E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
  • E01C19/48—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for laying-down the materials and consolidating them, or finishing the surface, e.g. slip forms therefor, forming kerbs or gutters in a continuous operation in situ
• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
  • E01C2301/00—Machine characteristics, parts or accessories not otherwise provided for
  • E01C2301/14—Extendable screeds
  • E01C2301/16—Laterally slidable screeds

Definitions

• the present invention refers to a screed of a paver finisher according to the p recharacterising part of the main claim.
• the paver finisher with such a screed also being part of the present invention.
• Prior Art Paver finishers of the prior art equipped with extendible screeds are known in a number of solutions.
• An extendible screed generally consists of a central fixed section, which determines the basic laying width, and of at least two sections which move perpendicularly to the centre line of the machine, sliding on a guide set, integral with the central section.
• the maximum laying width that can be achieved by an extendible screed, as described above and without the application of additional extensions is equal to or less than twice its basic width.
• the scope of the present invention is to avoid such disadvantages, realising an improved apparatus and machine.
• the invention is identified by the characterising part of the main claim, whose combined features allow all the problems described above to be solved.
• the present invention completely eliminates the aforementioned problems and allows a compact machine to be made that is capable of extending the laying width of a road pavement up to a maximum of 2.5 times the basic width of its screed.
• FIG. 1 - Figures 1, 2, 3, 4 and 12 represent solutions of the prior art, where Fig. 12 represents the solution most similar to the present invention, as previously mentioned.
• - Figures 5 and 6 show, according to the present invention, a schematic top view of the paver finisher and of its rear section respectively. Said rear section being substantially engineered to be towed (system not shown as part of the known art).
• Fig. 6 shows two section views of a road pavement, convex and concave respectively, made by the machine shown in Fig. 6.
• Fig. 7 shows the schematic cross section (Sect. B-B) of a screed sector of the present invention as shown in Fig. 6.
• Fig. 8 schematically shows the sliding system of an extendible screed sector, in this case the sector (1c) of Fig. 6.
• Fig. 9 represents a view of a vertical longitudinal section of Fig. 6, according to the present invention.
• Fig. 10 represents an alternative (traditional solution) to the extendible system of the auger set.
• a paver finisher (Fig.1) is a machine of known technology which always consists of two main units:
• the tractor (T) 1 which moves the whole screed unit, receives the material discharged by the trucks into a hopper (H) and feeds it to the screed unit (B) by means of conveyors (N 1 and N2), in turn followed by a set (C) of distributing augers (C 1 and C2).
• the screed unit (B) which spreads the material (asphalt mix, lean concrete, stabilized unbound mix) in a uniform layer, levelled and pre-compacted to make a road pavement.
• the overall transport width of the machine must comply with the limits allowed by the different countries, whilst the paving width must be advantageously wider to cover at least a road lane in a single pass.
• the screed must therefore be engineered so as to adjust its width to that more conveniently required by the work specifications.
• the extendible screeds consist of a central fixed sector, in turn consisting of two hinged sectors (B1) and (B2), connected to the tractor by two tow arms (A1) and (A2), and by two sectors (B3) and (B4) mobile in the direction of the laying width.
• the central sectors can be located ahead of the mobile sectors (Fig. 1 ), or behind them (Fig. 2) respectively.
• Each tow arm is rigidly connected to the central section of the screed, whilst the connection to the tractor is made through a ball joint which can be moved vertically.
• This type of constraint gives the screed a floating movement.
• the movement of the tractor (in the direction of the arrow) forces the screed to climb over the material with an angle of attack V, which is determined by the balance of the forces acting on the screed: tow force, screed weight, material resistance, material carrying capacity.
• the extendible sectors (B3) and (B4) generally move with respect to the central section by means of hydraulic cylinders, or by other known systems. Whenever the mobile sectors are extended outwards by more than approximately 800 mm it becomes necessary to fit additional auger sectors (C3) and (C4) to carry the material up to the outer ends of the screed and to remove said auger sectors whenever the mobile sectors are closed.
• the most common screeds can extend their basic width (L) up to twice (2L). Wider laying widths can be obtained by fitting individual extensions (B5, B6, B7, B8, ...) and the relevant necessary auger sectors (C5, C6, C7, C8 ). Also the solutions of Fig. 4 are of the known art, where sectors (B1b) and (B2b) are mobile with reference to sectors (B1a) and (B2a), in turn mobile with reference to fixed central sectors (B1 ) and (B2).
• FIGS 5 and 6 The subject of the invention is shown in Figures 5 and 6, in which are schematically represented: - The tractor (T) of a paver finisher, of the known art, comprising a receiving hopper (H), the conveyors (N 1 and N2) carrying the material toward the rear section of the machine, the tow arms (A1 ) and (A2) of the screed (B), a set (C) of distributing augers. - The screed unit (B) consisting of three elements, one fixed and two extendible, having such characteristics in order to reach a laying width at least equal to 2.5 times the width of the fixed central element (1a + 1 b).
• the hinge (Ac) being suitable to allow a proper actuator to incline the fixed sectors (1a), (1b) and the mobile right and left sectors (1d), (1c) so as to obtain a linear, convex, or concave pavement section profile.
• the preferential solution (Fig. 6) provides that the augers consist of two main elements (C1 ) and (C2) and of two auxiliary extendible side elements (2c) e (2d), where the function of said auxiliary elements can be replaced by an alternative less advantageous solution, consisting of sectors (Sd) and (Sc2) to be applied only when needed, according to the know art, as shown in Fig. 10.
• the screed (B) (Fig. 5) comprises a central fixed section, with a central hinge (Ac) (Fig. 6) on the centre line of the machine to constitute two sections (1a) and (1b), connected to the tow arms (A1 ) and (A2) respectively, plus two said mobile sectors (1c) and (1d) which can be extended in the direction perpendicular to the machine centre line, i.e. in the direction of the pavement width.
• an actuator of the known art by means of the hinge (Ac) can make an angle between the screed bottom plates of left sections (1a + 1c) and of right sections (1b + 1d) so as to make linear, convex, or concave (Fig. 6a) pavement section profiles.
• the mobile sectors (1c) and (1d) are located ahead of the central fixed sectors (1a) and (1 b); sector (1c) is in turn located ahead of sector (1d).
• the positions of sectors (1c) and (1d) can be interchanged, giving a totally equivalent functional solution.
• the screed end plates (3a) and (3b) are connected to the mobile sectors (1c) and (1d) respectively.
• the mobile sectors (1c) and (1d) each have a length about equal to that of the central sector (1a + 1b), of basic paving width "L", it is therefore possible to extend the overall paving width up to a value equal to or wider than 2.5 times the basic paving width "L". Operation
• Fig. 7 The characteristic items of a screed sector are schematically shown in Fig. 7.
• the material, spread by the augers in front of the screed (in the direction of the work progress) is forced by the tow action of the tractor to flow under the screed bottom plate (Pl), the flow being made easier by the alternate vertical movement of a tamper bar (Tp) which slightly extends underneath the leading edge of the screed bottom plate.
• Tp tamper bar
• Some screed versions do not include the tamper bar, and the flow of the material under the screed bottom plate is simply facilitated by the inclination V that is maintained by the plate with reference to the laying plane.
• Angle V is characteristic of any screed and represents the inclination assumed by the screed plate when all forces are balanced (traction, screed weight, resistance of material in front of the screed, friction between screed plate and material, material carrying force).
• Fig. 8 schematically shows how the sliding system of a mobile sector, with reference to the fixed sector, is preferably arranged, in this case sector (1c) of Fig. 6.
• Sector (1c) slides perpendicularly to the machine centre line, guided by a pair of supports (Sa) and (Sb), properly constrained to the support arm (4a).
• Sector (1d) slides as the above, being properly constrained to the support arm (4b).
• the support arms (4a) and (4b) being rigidly connected to the side ends of the central sectors (1a) and (1b) respectively.
• the core of the mobile screed sector (Fig. 7), which includes the screed plate (Pl), the tamper bar (Tp), the vibrators (Vb) and the screed plate heating equipment, is properly connected to the side walls (Wa) and (Wb) of the supporting frame (Ts).
• Said supporting frame comprises the guide (Gm) and an anti-rotation unit (Ar), sliding on bushings within the support (Sb), with wall (Wb) sliding on bushings along the external surface of the guide (Gf).
• the support (Sa) is connected to the support arm (4a), but it can move vertically with respect to the latter (see Fig. 9).
• the support (Sb) moves vertically along with the support (Sa), but it is possible to modify its angular position with respect to it around a rotation axis, coinciding with the centre line of the guide (Gf).
• the cylindrical guide (Gf) is rigidly connected to the support (Sa): the hydraulic cylinder (P) being rigidly connected to said guide (Gf) and with the centre line of said cylinder (P) coinciding with the centre line of said guide (Gf).
• the mobile guide (Gm) operated by the cylinder (P), slides on bushings inside the guide (Gf) and along its centre line.
• the section view A-A is shown in Fig. 9.
• the mobile screed sectors are not aligned crosswise with the central fixed screed sector, therefore it is necessary to adjust their vertical position independently so as to bring the trailed edges (Ua), (Ub) 1 (Uc) of all screed bottom plates (Pl) to lean upon the same plane, as shown in Fig. 9.
• the support (Sa) can move vertically along guides (Gv) with respect to the support arm
• the coupling of the tow arms (A1) and (A2) with the central screed sector is generally made as schematically shown in Fig. 9.
• a pin (Pn) on each side allows the inclination of the whole screed to be changed with respect to the tow arms (A1 ) and (A2) and to keep it locked in position by means of the turnbuckles (Tr) (one on each side).
• the support (Sb) can rotate around the centre line of the guide (Gf), dragging in the rotation the lower part of the relevant extendible sector.
• the adjustment is carried out by the screw adjuster (Rg) and by known locking devices (e.g.: bolts) to keep the position.
• known locking devices e.g.: bolts
• mouldboards (Rc) and (Rl) have been provided in order to limit the thickness of the material fed to the central screed sectors (1a) and (1 b) and to the most backward mobile screed sector (1d).
• the vertical displacement of the mouldboard (Rc) is operated by hydraulic cylinders, or by other known devices (not shown).
• the horizontal guide (Go) is fixed to the mouldboard (Rc); the side mouldboard (Rl) can slide within said guide (Go); said mouldboard (Rl) being moved by the mobile sector (1d) in a direction perpendicular to the machine centre line; on the end plate
• the vertical movements of the mouldboards (Rc) and (Rl) are managed by an automatic control system of the thickness of the material being supplied by the augers to the screed sectors (1a), (1b) and (1d).
• the cross beam (5) supporting the auger set (C1) and (C2), is connected to the tractor in such a way as to be moved in a vertical direction.
• Two guides (Gc) are fixed to the cross beam (5); within said guides the support arms (2a) and (2b), of the auxiliary auger sectors (2c) and (2d) respectively, can slide in a direction perpendicular to the machine centre line; said auxiliary auger sectors (2c) and (2d) being located just behind the main augers (C1) and (C2) in the direction of the paving work progress.
• the support arms (2a) and (2b) are independently operated by hydraulic cylinders, or by other known systems.
• the solution allows the auxiliary auger sets to move vertically along with the main augers, whilst the cross movements of the support arms (2a) and (2b) are operated in synchronisation with the movements of the relevant screed mobile sectors whenever they are extended more than a preset value (about 800 mm), or return below said value in the closing phase.
• Fig. 12 compares a solution similar to that of the invention, but with evident disadvantages:
• a screed for a paver finisher (Fig. 6) of the type comprising sectors (1c) and (1d), independently extendible and retractable, substantially sliding on guides connected to the support arms (4a) and (4b) respectively, in turn solid with the central screed fixed sectors (1a) and (1b) respectively.
• Said extendible sectors (1c) and (1d) being located one behind the other and ahead of the central fixed screed sectors, in the direction of the paving work progress.
• Said extendible sectors (1c) and (1d) therefore being able to have a length similar to that of the whole central sector (1a + 1b), having a basic laying width "L".
• Said solution being suitable for obtaining a maximum laying width of at least 2.5 times the basic laying width "L”.
• Said screed consisting of: - a central fixed section of a certain basic length "L”, with a central hinge (Ac), parallel to the machine centre line, constituting two units (1a) and (1b) articulated to give a linear, convex, or concave profile of the mat cross section (Fig. 6a); said units (1a) and (1 b) being fitted, at their external ends, with the support arms (4a) and (4b) of the extendible sectors (1c) e (1d) respectively.
• first extendible sector (1d) with a length about equal to that of the whole central sector (1a + 1b) and located ahead of this in the direction of the paving work progress.
• second extendible sector (1c) with a length about equal to that of the whole central sector (1a + 1 b) and located ahead of the first extendible sector (1d) in the sense of the paving work progress, said extendible sectors (1c), (1d) being independently mobile in respect of the central sector (1a + 1b) in the sense of the laying width and in vertical direction.
• a screed as above, where said extendible sectors (1c), (1d) are connected to the support arms (4a) e (4b) respectively, which are part of the central section, by means of height adjusting devices (Rc), (Gv) Fig. 9.; said height adjustment being necessary to obtain the co-planarity of the trailed edges (Uc), (Ud) of the screed bottom plates of the extendible sectors (1c), (1d) respectively with the relevant trailed edges of the bottom plates (Ua) and (Ub) of the central sectors (1a) and (1b) respectively.
• a screed as above, where each extendible sector is equipped with devices (Sb), (Rg) (Fig.
• mouldboard (Rc) sliding in a vertical direction within the guides (Gv) fixed to the tow arms (A1) and (A2) and being moved by hydraulic cylinders, or by equivalent functional devices; said mouldboard (Rc) being fitted with a horizontal guide (Go) to support a further mouldboard (Rl) limiting the height of the material layer fed by the augers to the most backward extendible sector (1d), in the direction of the paving work progress.
• Said mouldboard (Rl) being mobile in a vertical direction, solid with the first mouldboard (Rc), and crosswise along with the movement of the extendible section (1d); said mouldboard (Rl) being connected to the end plate (3b).
• Said auxiliary augers (2c) and (2d) being operated together with the main auger sectors (C1) and (C2) respectively and said auxiliary augers being extendible crosswise, in a direction perpendicular to the machine centre line, with movements controlled by the extension, or closing of the relevant mobile screed sectors (1c) and (1d).
• auxiliary augers (2c) and (2d) being supported by arms (2a) and (2b) respectively, sliding within guides (Gc) by means of known devices, where said guides (Gc) are fixed to the crossbeam (5), supporting the main augers (C1 ) and (C2).

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• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Road Paving Machines (AREA)

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• 2007
  • 2007-09-18 EP EP07818213.6A patent/EP2201176B1/de not_active Not-in-force
  • 2007-09-18 WO PCT/EP2007/008111 patent/WO2009036779A1/en not_active Ceased

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