Screed Plate for Paving Machine

Description

TECHNICAL FIELD

This patent disclosure relates generally to mobile paving machines for conducting a paving operation and, more particularly, to a floating screed assembly for distributing and compacting the paving material to produce a paving mat.

BACKGROUND

Mobile paving machines, referred to as road pavers, are used during a paving operation to apply, spread, and compact paving material into a paving mat over the ground or road bed to produce a smooth, hard surface such as a roadway, parking lot or other paved area for cars, trucks, and other vehicles to travel upon. A typical example of paving material to produce a paved surface is a hot asphalt mix of hard aggregates like rocks, finer materials like sand, and a bitumen mixer or binder, and possibly other additives and modifiers. The paving material is initially in a loose, almost fluid, state to facilitate spreading and distribution over the work surface and to cover the desired areas.

To distribute the paving material, the mobile paver may be operatively associated with a screed assembly that is attached to and towed along the travel direction of the paver. The screed assembly includes one or more flat metal screed plates attached to the underside of a screed frame. The mobile paver delivers the paving material to the work surface in front of the forward leading edge of the screed plate, which is moved over the distributed material by the forward travel of the mobile paver. The floating screed assembly may be self-leveling and attached to the mobile paver to freely float over the distributed paving material, and the weight of the screed assembly and the flatness of the screed plates spreads and compacts the paving material to form a paving mat. In possible variations, the screed assembly may be configured to vibrate to improve compaction of the paving material and the screed plate can be heated to prevent the paving material from adhering thereto.

It is typically desirable to distribute the paving material as evenly and homogenously as possible to produce a paving mat with sufficient density and smoothness to serve as a roadway or similar paved surface subjected to the repeated passing of vehicles and changing weather conditions. To improve the homogenous and even distribution of aggregates and fines within the asphalt mix, U.S. Patent 10,156,050 (“the ’050 patent”) describes a screed assembly having screed plates with a textured surface thereon. The textured surface may include corrugations arranged parallel or perpendicular to the direction of travel of the mobile paver. The ’050 patent describes that texturing of the underside of the screed plate produces a more homogenous sorting and distribution of aggregates in the paving material and thus a more durable paved surface.

SUMMARY

The disclosure describes, in one aspect, a screed plate for a screed assembly towed by a mobile paver that includes a forward leading edge and a rearward trailing edge parallel to the forward leading edge. The screed plate also includes an upper attachment surface extending between the forward leading edge and the rearward trailing edge and a lower textured surface opposite the upper attachment surface. The lower textured surface has a plurality of protruding elements each including a leading element front oriented toward a forwardly toward the leading edge and a rearward trailing stern oriented toward the rearward trailing edge. To improve wear characteristics, the leading element front has a first surface area that is greater than a second surface area of the trailing element stern.

In another aspect, the disclosure describes a screed plate for a screed assembly towed by a mobile paver. The screed plate includes a forward leading edge and a rearward trailing edge parallel to the forward leading edge. The screed plate also includes an upper attachment surface extending between the forward leading edge and the rearward trailing edge and a lower textured surface opposite the upper attachment surface. The lower textured surface has a plurality of protruding polyhedron elements each including an element base and an element apex. The plurality of protruding polyhedron elements further each include a leading edge and a trailing edge extending between the element base and the element apex, wherein the leading edge is longer than the trailing edge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a mobile paver with a screed assembly moving in a travel direction to produce a homogenous paving mat over a work surface.

FIG. 2 is a forward perspective view of a screed assembly configured with screed extenders laterally extended from the screed frame and a plurality of textured screed plates attached to the underside of the screed frame.

FIG. 3 is a perspective view of the underside of a textured lower surface of a screed plate having a plurality of protruding polyhedron elements located between the forward leading edge and the rearward trailing edge in accordance with the disclosure.

FIG. 4 is a perspective view of an example of the protruding polyhedron element embodied as a rhombic pyramid having a forward leading element front with a surface area larger than that of a rearward trailing element stern.

FIG. 5 is a perspective view of an example of the protruding polyhedron element embodied as a kite-shape pyramid having a pair of longer forward leading edges and shorter rearward trailing edges.

FIG. 6 is a perspective view of an example of the protruding element in the shape of a three-dimensional teardrop having a tapering forward leading element front and a curved rearward trailing element stern.

FIG. 7 is top plan schematic of an example of the lowered textured surface of the screed plate with the plurality of protruding polyhedrons elements arranged in a matrix.

FIG. 8 is a top plan schematic of an example of the lower textured surface of the screed plate with the protruding polyhedrons elements arranged in a staggered gradation pattern.

FIG. 9 is a side elevation view of the textured screed plate showing the lateral element rows having different element heights progressively leveling toward a lateral band at the rearward trailing edge.

DETAILED DESCRIPTION

Now referring to the drawings, wherein whenever possible like reference numbers will refer to like elements, there is illustrated in FIG. 1 an example of a mobile paving machine or paver 100 for laying down paving material 102 on the ground, roadbed, or another work surface 104 to produce a paving mat 106 that paves over and covers the work surface resulting in a paved surface. The finished paved surface may be intended as a roadway, highway, structural foundation or other surface having hardness, flatness and durability characteristics to sustain repeated vehicular traffic and endure changing weather conditions, including temperature changes and precipitation. To distribute the paving material 102 over the work surface 104, the mobile paver 100 can be self-propelled and operated to travel in a travel direction 108 that is aligned with the longitudinal axis or orientation of the paver. As used herein, the terms “forward” or “leading” may refer to the forward direction of the mobile paver 100 when traveling in the travel direction 108, and the terms “aft,” “rearward” or “trailing” may refer to the direction rearward of the mobile paver.

To accommodate and carry paving material 102 prior to distribution on the work surface 104, the mobile paver 100 can include a hopper 110 that is supported on a machine frame or chassis 112 that is the loadbearing structural support and framework of the paver. The hopper 110 can be an opened box-like structure or bin including upward extending sidewalls 114 that are laterally opposed and that contain the paving material 102 deposited therein. The hopper 110 can be located at the forward end of the mobile paver 100 and can receive paving material 102 from above via a transport vehicle such as a dump truck. As the paving material is distributed from the mobile paver 100, the hopper 110 can be regularly replenished with fresh paving material delivered from an asphalt plant or facility.

To direct the loose, granular paving material rearward from the hopper 110, the mobile paver 100 includes a conveyor system 116 that extends through and is supported by the chassis 112. The conveyor system 116 may include one or more conveyor belts that translate about rotating pulleys or drums to move the paving material 102 rearward and discharge the material from the mobile paver 100 to the work surface 104.

To propel the mobile paver 100 over the work surface 104 during a paving operation, the chassis 112 can be supported on a plurality of ground engaging elements 118 that direct and transfer traction and propulsion forces to the work surface 104. An example of the ground engaging element 118 can be continuous tracks that are looped as a belt around a plurality of drive sprockets that can rotate with respect to the chassis 112. The continuous tracks translate with respect to the chassis 112 to move the mobile paver 100 over the work surface 104. Another example of ground engaging elements 118 can be rotatable wheels journalled to the chassis 112.

To generate motive power and drive the ground engaging elements 118, the mobile paver 100 can include an engine 120 supported on the chassis 112. The engine 120 can be a conventional internal combustion engine that combusts a hydrocarbon-based fuel to convert the lateral chemical energy therein to motive power for propulsion and other work. The engine 120 can also be associated with a generator 122 to generate electricity for powering the electrical system of the mobile paver 100. In other possible configurations, the mobile paver 100 can include an electrical powertrain and can be operatively driven by a plurality of electrical storage batteries or fuel cells.

To accommodate an operator for steering and controlling the mobile paver 100, an operator station 124 or operator cab can be situated on top of the chassis 112 in a location providing visibility over the work surface 104. Located in the operator station 124 can be various controls and input control devices 126 such as a steering wheel to alter the travel direction 108 of the mobile paver 100, accelerator and brake pedals, gear and direction shifters, and the like. To visually interface with the operator, the operator station can include an instrument console 128 having various dials, readouts, display screens and the like. Moreover, the input control devices 126 and the instrument console 128 can be associated with an electronic controller configured or programmed to receive and process data and information to assist in operation of the mobile paver 100.

To more evenly distribute the paving material 102, a screed assembly 130 can be coupled to the rear end of the chassis 112 that can be moved over the deposited paving material 102 by the forward travel of the mobile paver 100 in the travel direction 108. The screed assembly 130 can be associated with an auger 132 located rearward and below the conveyor system 116 and arranged to direct and move the loose paving material 102 discharged therefrom laterally towards the sides of the chassis 112. The auger 132 is arranged in a lateral direction 134 or axis that is perpendicular to the forward and rearward travel directions 108 and at right angles to the longitudinal axis of the chassis 112. Moreover, the auger 132 is vertically adjacent to the work surface 104 and establishes a vertical direction 135 normal to both the travel direction 108 and the lateral direction 134. The auger 132 can be an elongated rotating structure with oppositely directed spiral or helical flights that push the paving material 102 laterally outward when rotated.

To compress and smooth the granular paving material 102 laterally distributed by the auger 132, the screed assembly 130 includes one or more screed plates 136 that are attached to the underside of a screed frame 138. The screed plates 136 are metal plates adapted to contact and slide over the paving material 102 deposited on the work surface 104, and the weight and load of the screed frame 138 compresses the loose paving material 102 into the denser, harder paving mat 106. By way of example, the material of the screed plates 136 can be cast nickel or hardened steel.

To increase the compressive forces applied to the paving mat 106, the screed frame 138 can include internal eccentric weights that generate vibrating forces in the vertical direction 135 that vibrate the screed plates 136 contacting the paving material 102. To prevent the paving material 102 from cooling and adhering to the screed plates 136, the screed assembly 130 can be associated with inductive heaters located in the screed frame 138.

To adjust the thickness of the paving mat 106, the screed assembly 130 can be pivotally connected to the chassis 112 by one or more tow arms 140. The tow arms 140 are pivotal so that the screed frame 138 can be pivotally tilted with respect to the chassis 112 to adjust the angle of attack, or the angle that the screed plates 136 encounter and come into contact with the paving material 102 exiting the conveyor system 116 onto the work surface 104. Adjusting the angle of attach enables the screed plates 136 to move and slide over the paving material 102 allowing the screed assembly 130 to float with respect to the work surface 104. To raise and lower the screed assembly 130 in the vertical direction 135 to contact and disengage from the work surface 104, one or more extendable and retractable hydraulic lift cylinders 141 can also be connected between the chassis 112 and the screed frame 138.

Referring to FIG. 2, the screed assembly 130 can be extendable in the lateral direction 134 to adjust the lateral width of the screed frame 138. For example, the screed frame 138 can include a main screed section 142 and first and second extender screed sections 144 located toward the opposite lateral ends of the screed assembly 130. The extender screed sections 144 can be located behind the main screed section 142 and the structures can be slidingly connected together, for example, by a sliding dovetail rail. In another configuration, the extender screed sections 144 can be mounted toward the front of the screed frame 138 with respect to the travel direction 108.

The screed assembly 130 can also include hydraulically actuated extender cylinders 146 that operatively connect the main screed section 142 with the first and second extender screed sections 144. Actuation of the extender cylinders 146 moves the first and second extender screed sections 144 in the lateral direction 134 with respect to the main screed section 142. To retain the lateral distribution of the paving material 102, the first and second extender screed sections 144 can each include a lateral flange 148 or blades parallel to and aligned in the travel direction 108.

The screed plates 136 can be removably attached to the underside of main screed section 142 and the first and second extender screed sections 144. A plurality of screed plates 136 can extend across the lateral width of the screed frame 138 to produce a continuously smooth flat paving mat 106 across the lateral direction 134 and extending rearward of the screed assembly 130 in the travel direction 108.

The front of the screed frame 138 may also include a forward panel that extends upward from the intersection with the screed plates 136 that may be configured as a solid planar panel extending in the lateral direction 134. The front of the screed frame 138 pushes excess paving material 102 discharged from the conveyor system forward in the travel direction 108 until the material flows under and is compressed by the screed plates 136. The screed assembly 130 may also include a tamper bar adjacent the front of the screed frame 138 that can be rapidly and repeatedly moved upward and downward in the vertical direction 135 to tamper and compact the paving material flowing underneath the screed plates 136.

Referring to FIG. 3, each screed plate 136 can be generally rectangular in shape, having a rectangular outline 150 or perimeter, and can have a lower textured surface 152 and an upper attachment surface 154 opposite the lowered textured surface. When the screed plates 136 are attached to the screed frame, the lower textured surface 152 is oriented to interface with the paving material that moves thereunder and the upper attachment surface 154 is in abutting contact with the screed frame. The upper attachment surface 154 can be flat and planar, although in some configurations, the upper attachment surface 154 can include mounting and attachment features to secure the screed plate 136 to the screed frame.

The lower textured surface 152 and the upper attachment surface 154 can extend between a forward leading edge 156 and a rearward trailing edge 158 of the rectangular plate outline 150. The terms forward leading edge 156 and a rearward trailing edge 158 are in reference to the travel direction 108 of the mobile paver and reflect movement of the screed plate 136 with respect to the work surface.

The forward leading edge 156 and a rearward trailing edge 158 may be linear and parallel to each other in the lateral direction 134. The distance between the forward leading edge 156 and a rearward trailing edge 158 corresponds to the longitudinal length of the screed plate 136 and may be coextensive with the length of the screed frame in the travel direction 108. To assist directing the paving material underneath the screed plate 136, the forward leading edge 156 may be slightly turned up in the vertical direction 135.

The rectangular plate outline 150 can also include parallel first and second side edges 160, 162 that extend between the forward leading edge 156 and the rearward trailing edge 158. The distance between the first and second side edges 160, 162 corresponds to the width of the screen plate 136 in the lateral direction 134. The first and second side edges 160, 162 can be linear and flat to abut seamlessly against the side edges of adjacent screed plates 136 when attached to the screed frame.

To improve mixing of the paving material passing underneath the screed plate 130, the lower textured surface 152 can have a three dimensional textured pattern of protruding elements 166 and corresponding channeling grooves 168 located there between that impress an unevenness to the screed plate 136. The three dimensional topology of the lower textured surface 152 thus has structural variation with respect to the vertical direction 135. The structural unevenness and topographic variability of the lowered textured surface 152 may displace larger aggregates within the paving material. The movement and shifting of the paving material caused by the lowered textured surface 152 may further embed the aggregates within the fines and binders, resulting in a denser and harder paving mat. Further, the additional mixing caused by the lower textured surface 152 may result in a more homogenous consistency of the aggregates and fines within the paving material 102, also resulting in improvement in the characteristics of the produced paving mat 106.

Referring to FIG. 3, to structurally form the lower textured surface 152 of the screed plate 136, a textured pattern 164 can be included that has a plurality of protruding elements 166 that are spaced apart by a corresponding plurality of channeling grooves 168 located between the elements. The protruding elements 166 have a three-dimensional structural extension that projects downward from the screed plate 136 in the vertical direction 135 and that can be tapered with converging sidewalls as described below. The plurality of channeling grooves 168 can extend between the plurality of protruding elements 166 in the travel direction 108 generally between the forward leading edge 156 and the rearward trailing edge 158. The textured pattern 164 therefore has a variable topology and elevation created by the plurality of protruding elements 166 and channeling grooves 168 across the underside of the lower textured surface 152.

In an example described further below, the plurality of protruding elements 166 may be staggered and interspersed with the textured pattern 164 such that the channeling grooves 168 are crooked or laterally shifted with respect to the lateral direction 134. The channeling grooves 168 may assume a crooked or zigzag direction with respect to the lateral direction 134 as the channeling grooves extend from the forward leading edge 156 toward the rearward trailing edge 158. The plurality of protruding elements 166 can also be randomly located in the textured pattern 164 such that the channeling grooves 168 are generally crooked or staggered in orientation with respect to the travel direction 108.

When the screed plate 136 moves in the travel direction 108 with respect to the paving material, the solid protruding elements 166 displace the paving material 102 into the plurality of channeling groove 168 to continue mixing and blending. The staggered or zigzag pattern of the channeling groove 168 can further blend the paving material. Moreover, the protruding elements 166 can strike and displace the larger or coarser aggregates in the paving material 102 to better mix and embed the aggregates in the binding mixture. As a result, the textured pattern 164 on the screed plate 136 produces a more homogenous mix of the paving material 102 and a more uniformly dense paving mat 106 behind the trailing edge 158.

Referring to FIG. 4, in an example, the protruding elements 166 can be structurally configured as a polyhedron, or a three-dimensional shape having polygonal faces that intersect each other to form sharp angular corners or vertexes. The protruding polyhedron element 170 may include a polygon shaped element base 172 that extends in elevation and converges to a common apex 174. The element base 172 can have multiple linear sides that intersect each other. An element face 176 extends between each linear side or edge of the element base 172 and converges to the common element apex 174. The distance between the element base 172 and the element apex 174 defines the element height 178 in the vertical direction 135. By way of example, the element base 172 may have a length of approximately 4 inches, or 100 mm, and may have a width of approximately 2 inches, or 50 mm.

When included in the textured pattern, the protruding polyhedron elements 170 can be aligned in the travel direction 108 and are characterized as having a forwardly directed leading element front 180 and an opposite, rearward directed trailing element stern 182. When the screed plate 136 moves in the travel direction 108 with respect to the work surface, the leading element front 180 encounters and displaces the paving material into the corresponding channeling grooves at the lateral sides of the of the protruding polyhedron element 170. The rearward structure of the protruding polyhedron element 170 terminates in the trailing element stern 182 wherein the channeling grooves can converge together again. The leading element front 180 and the trailing element stern 182 can be designed and configured differently to interact with the paving materials in a manner that improves the construction and use of the screed plate 136.

For example, to improve the wear characteristics of the screed plate 136, the protruding polyhedron elements 170 can be produced with irregular geometric shapes such that the surface area of the leading element front 180 is larger than the surface area associated with the trailing element stern 182. Due to the larger surface area, the protruding polyhedron element 170 has a greater amount and volume of material directed toward the leading element front 180 than with respect to trailing element stern 182. The additional material at the leading element front 180 improves the durability of the protruding polyhedron elements 170 and may prolong the functional life or operative duration of the textured pattern 164. Further, by increasing the surface area associated with the leading element front 180, the cumulative frictional forces resulting from contact with the paving materials are better dissipated about the protruding polyhedron elements 170. Comparatively reducing the surface area associated with the trailing element stern 182 results in a corresponding reduction of material usage and weight for each of the protruding polyhedron elements 170 and collectively for the screed plate 136.

To conform with the irregular shape of the protruding polyhedron element 170, the two element faces 176 corresponding to the leading element front 180 can comprise a pair of leading faces forwardly oriented in the travel direction that intersect along a leading edge 184 that extends angularly from the element base 172 to the element apex 174. The irregular shaped protruding polyhedron 170 can also have two the element faces 176 associated with the trailing element stern 182 and directed rearward with respect to the travel direction 108 that form a pair of trailing faces that are intersected and cut by a truncation face 186. The truncation face 186 may extend at an angle from the element base 172 to angularly intersect with the leading edge 184 of the leading element front 180.

The element base 172 of the irregular protruding polyhedron element 170 assumes the shape of an irregular polygon having sides or edges of different lengths. For example, the sides or leading edges 188 where the two leading element faces 176 associated with the leading element front 180 may be dimensionally longer than the trailing edges 189 formed where the trailing element faces 176 intersect the element base 172. In particular, the trailing edges 189 may be cut short by intersection with the truncation face 186 and are thus dimensionally shorter that the leading edges 188. The element base 172 may therefore appear as an irregular five-sided pentagon. As a result, the volume of the protruding polyhedron element 170 associated with the trailing element stern 182 is less than the volume associated with the leading element front 180. In addition, the length of the leading edges 184 between the element base 172 and the element apex 14 may be longer than the length of the truncation face 186 between the features, as a result of the different angles that leading edge 184 and the truncation face 186 intersect to the element base 172.

The truncation face 186 may extend from the element base 172 at an angle such that the element apex 174 is generally formed as a continuation of the truncation face 186. Accordingly, the element apex 174 may be truncated, as opposed to a sharp cornered vertex. Moreover, the acute angle at which the leading element front 180 interfaces with the paving material may reduce the associated contact friction.

Referring to FIG. 5, in another example, the protruding element may be configured as a rhombic pyramid 190 having an element base 192 in the shape of a four-sided kite from which extends polygonal element faces 196 that taper and converge at an element apex 194. The distance between the element base 192 and the element apex 194 establishes the vertical height 198 of the rhombic pyramid 190 in the vertical direction 135.

The rhombic pyramid 190 can be further characterized as having a leading element front 200 forwardly directed in the travel direction 108 and an opposite rearward trailing element stern 202 having different associated surface areas. For example, the pair of element faces 196 associated with the leading element front 200 may intersect along a leading edge 204 and the pair of element faces 16 corresponding to the trailing element stern 202 can intersect along a trailing edge 206. The leading edge 204 and the trailing edge 206 can angularly extend from the element base 192 to intersect and converge together at the element apex 194.

The length of the leading edge 204 can be larger than the length of the trailing edge 206. Accordingly, the leading element front 200 can be associated with additional leading edges 208, formed where the pair of element faces 196 intersect the element base 192, that are shorted than additional trailing edges 209 formed by the intersection between the element faces 196 of the trailing element stern 202 and the element base 192. Moreover, the angle at which the trailing edge 206 extends from the element base 192 may be greater than the angle of the leading edge 204 with the element base 192. In fact, the angle of intersection between the trailing edge 206 and the element base 192 can assume any value greater than the corresponding angle between the leading edge 204 and the element base 192. As a result, the volume associated with the leading element front 200 of the rhombic pyramid 190 is larger than the volume associated with the trailing element stern 202.

Referring to FIG. 6, in yet another example, the protruding element can be configured as a partially curved structure having a teardrop shape. The protruding teardrop element 210 can have an element base 212 that is outlined as a teardrop and may have a plurality of element faces 216 that extend and converge at an element apex 214, the vertical distance between which establishes an element height 218. To conform to the teardrop outline, the protruding teardrop element 210 has a leading element front 220 that has an elongated tapered shape and a trailing element stern that is rounded or curved. The tapered leading element front 220 can be formed by convergence of two of the forwardly directed element faces 216 along a leading edge 224 that extends between the element base 212 and the element apex 214.

In contrast to the leading element front 220, the trailing element stern 202 can be a rounded or curved surface between the element base 212 and the element apex 214. For example, the trailing element stern 202 can have a curved or U-shaped trailing edge 226 that corresponds with the intersection of the element base 212. The length of the leading edge 224 between the element base 212 and the element apex 214 can be larger than the corresponding length of the curved trailing element stern 202. Accordingly, the resulting volume associated with the leading element front 200 is greater than the volume associated with the trailing stern 202.

The plurality of protruding elements 166 producing the textured surface 164 can have different arrangements to improve the interaction with and mixing of the paving material. For example, referring to FIG. 7, the protruding elements 166 can be arranged in a grid-like textured matrix pattern 230 having a plurality of successive lateral element rows 232 that are parallel to the forward leading edge 152 and the rearward trailing edge 158 and thus are aligned in the lateral direction 134. The protruding elements 166 can be shaped as the protruding polyhedrons elements, such as rhombic pyramids or kites as described above, and may each include a longer major diagonal 234 that extends between two opposite vertices of the polyhedron shape. The plurality of protruding elements 166 can be arranged within the textured matrix pattern 230 such that major diagonals 234 are aligned parallel with the travel direction 108 of the screed plate 136.

The successive lateral element rows 232 may include, for example, a first lateral element row 236 that is proximate to the forward leading edge 156 of the screed plate 136 and a second lateral element row 238 located toward the rearward trailing edge 158. The protruding elements 166 in the first and second lateral element rows 236, 238 can be aligned with each other in the travel direction 108. For example, in the embodiment of protruding polyhedron elements, the major diagonals 234 of the protruding polyhedron elements 170 in the first lateral element row 236 align with the major diagonals 234 of the protruding polyhedron elements 170 in the second lateral element row 238.

In addition, to stagger or alternate the textured matrix pattern 230, an intermediate lateral element row 239 can be included that intermittently intersperses with the protruding elements 166 between the first and second lateral element rows 236, 238. In particular, the major diagonals 234 of the protruding elements 166 in the intermediate lateral element row 239 are offset in the lateral direction 134 with respect to the major diagonals 234 of the protruding elements in the first and second lateral element rows 236, 238. The protruding elements 166 of the intermediate lateral element row 239 can extend partially alongside the protruding elements of the first and second lateral element rows 236, 238 with respect to the travel direction 108. The interspersing of protruding elements 166 within the intermediate lateral element row 239 can assist in the lateral shifting and staggering of the channeling grooves 168 with respect to the lateral direction 134.

In the example of FIG. 7, the protruding elements 166 in the successive lateral element rows 234 can have any of the foregoing configurations and shapes, and may be identical to each other within the textured matrix pattern 230. In another example shown in FIG. 8, the protruding elements 166 may have different sizes and/or shapes that change with respect to the travel direction 108 to produce a textured gradation pattern 240 on the screed plate. For example, rather than having a consistent topology, the textured gradation pattern 240 is characterized by changes in the concentration and density of the protruding elements 166 between the forward leading edge 156 and the rearward trailing edge 158.

For example, the geometric shapes of the plurality of protruding elements 166 can be organized in successive lateral element rows 242 and can vary in surface area in the travel direction 108 between the forward leading and rearward trailing edges 156, 158. In other possible embodiments, the geometric shapes of the protruding elements might vary between the successive lateral element rows 242. The plurality of protruding elements 166 may each have an outline and shape of the polyhedrons described above and may each have a longer major diagonal 244 extending between the leading vertex and the trailing vertex that is aligned parallel with the travel direction 108.

The textured gradation pattern 240 can also be characterized by varying the number of protruding elements 166 over the length of the screed plate 136 between the forward leading edge 156 and the rearward trailing edge 158. For example, the number of protruding elements 166 may increase with respect to the travel direction 108 between the between the forward leading edge 156 and the rearward trailing edge 158. In particular, the first lateral element row 246 may have fewer protruding elements 166 compared to the larger number of protruding elements 166 in the second lateral element row 248. The increase in the number of protruding elements 166 may also be referred to as increasing the density or concentration of the protruding elements.

The number of protruding elements 166 might double between successive lateral element rows 242 or groupings of lateral element rows. For example, a first lateral element row 246 may include four protruding elements 166, which may be embodied as oblong rhombic or diamond shaped elements described above. The first lateral element row 246 can be adjacent to the forward leading edge 156 of the screed plate. A second set or grouping of lateral element rows 248 can be rearward and parallel to the first lateral element row 246 and can have eight protruding elements 166 that may also have oblong rhombic or diamond shapes. The textured gradation pattern 240 may also include a third set or grouping of lateral element rows 249 that is a rearward and parallel to the second lateral element rows 248 and may have sixteen protruding elements 166.

Thus, the textured gradation pattern 240 can be characterized by numerically doubling the number of protruding elements 166 in successive lateral element rows 242, including the first lateral element row 246, the second lateral element row 248, and the third lateral element row 249. The textured gradation pattern 240 thus has an increasing density or concentration of protruding elements 166 between the successive parallel lateral element rows 242 of the screed plate 136.

Conversely, the difference in the number of protruding elements 166 between the first lateral element row 246 and the second lateral element row 248 can be characterized as a progressive reduction in the size of the protruding elements 166. In the example in which the number of protruding elements 166 doubles between successive lateral element rows 242, the size of the major diagonals 244 of the protruding elements 166 may be correspondingly reduced by one half, resulting in a corresponding reduction in the size of the base area and volume of the protruding elements. By way of example, the major diagonals 244 of the protruding elements 166 in the first lateral element row 246 may be approximately 4 inches or 100 mm, and may have a minor diagonal of 2 inches or 50 mm. The dimensions of the protruding elements 166 in the second lateral element row 248 can be reduced by approximately one half. Further, reducing the size of the protruding element 166 in successive lateral element rows 242 enables inclusion of a larger number of protruding elements per row.

Decreasing the size of the protruding elements 166 while simultaneously increasing the number of protruding polyhedron elements 166 between successive lateral element rows 242 may result or enable the protruding elements 166 to be staggered and interspersed with each other. For example, the protruding elements 166 of the second lateral element row 248 may be laterally staggered and offset in the lateral direction 134 with respect to the protruding elements 166 of the first lateral element row 246. More particularly, the major diagonals 244 of the protruding polyhedron elements 170 of the second lateral element row 248, which are aligned and parallel with the travel direction 108, can be laterally staggered and offset in the lateral direction 134 with respect to the major diagonals 244 of the protruding elements 166 in the first lateral element row 246.

Further, the major diagonals 244 of the protruding elements 166 in the third lateral element row 249 can be laterally staggered and offset with respect to the major diagonals 244 of the protruding elements 166 in the second lateral element row 248. The major diagonals 244 of the third lateral element row 249 can be longitudinally aligned with the major diagonals 244 of the first lateral element row 246 with respect to the travel direction 108. The lateral offset of the protruding elements between successive lateral element rows staggers the protruding elements as shown.

The textured gradation pattern 134 may also be characterized by an increased branching or frequency of the plurality of channeling grooves 168 formed between the protruding elements 166. For example, as the number protruding elements 166 increases between the successive lateral element rows 242, the corresponding number of channeling grooves 168 may also increase thereby, resulting in a branching of the channeling grooves with respect to the lateral direction 134. In the example where the number of protruding elements 166 doubles between successive lateral elements rows 242, the number of channeling grooves 168 increasingly branches and may correspondingly double numerically. The density or concentration of the channeling grooves 168 in the textured gradation pattern 240 therefore also increases between the forward leading and rearward trailing edges 156, 158 of the screed plate 136. The increase in channeling grooves 168 also has the effect of further mixing and blending the paving material directed between the protruding elements 166.

INDUSTRIAL APPLICABILITY

A screed plate 136 having a lowered textured surface 152 including a plurality of protruding elements of the foregoing shapes and configurations can be used to spread and compact paving material during a paving operation as described with reference to the proceeding figures. During the paving operation, paving material 102 in loose, granular form, including aggregates of different sizes (i.e. coarse and fine) in a binder or bitumen mixture, is delivered to the hopper 110, directed through the chassis 112 by the conveyor system 116, and discharged to the auger 132 to be laterally spread over the work surface 104 in the lateral direction 134. The screed assembly 130, which may be attached to the mobile paver 100, can be towed over the deposited paving material 102 so that the screed plates 136 attached to the underside of the screed frame 138 move over the paving material in the travel direction 108.

Referring to FIG. 3, as the paving material encounters the textured pattern 134 due to relative movement of the screed plate 136 in the travel direction 108, the plurality of protruding elements 166 directs the paving material into the corresponding plurality of channeling grooves 168 formed between the protruding elements 166. Moreover, the protruding elements 166 can strike and displace the larger or coarser aggregates in the paving material 102 to better mix and embed the aggregates in the binding mixture. Interaction between the plurality of protruding elements 166 and the paving material 102 mixes and blends the paving material during initial compaction under the screed plate 136, resulting in a more homogenous mix and denser paving mat 106

Where the protruding elements 166 have a generally tapered shape oriented toward the leading edge 156 of the screed plates, as shown in the examples of FIGS. 4-6, the paving material initially encounters and interacts with the leading element front 180 having a significant or large surface area. For example, by increasing relative lengths of the forward pair of element faces 176 and elongating the leading edge 204, the leading element front 180 of the protruding element is larger in area and volume than the trailing element stern 182.

The leading element front 180 therefore has a relatively larger size and volume of metallic material that can be worn down during the paving and compacting operations. Furthermore, the increased surface area and the reduced angle at which the leading element front 180 encounters the paving material better distributes the resulting contact friction. Thus, the increased surface area associated with the leading element front 180 improves the service life of the screed plates 136. Correspondingly, the relatively reduced surface area associated with the trailing element stern 182 of the protruding elements 166 reduces the weigh and material usage associated with the screed plate 136.

Referring particularly to FIG. 2, as the screed plate 136 moves over the paving material, the textured pattern 164 on the underside may arrange the paving material into a plurality of paving windrows 260 formed following the trailing edge 158 of the screed plate 136 in the travel direction 108. In an embodiment, to reduce the appearance or noticeability of paving windrows 260, the textured pattern 164 can be configured to taper or reduce in height between the leading edge 156 and the trailing edge 158. For example, referring to the side elevational view of FIG. 5, the protruding elements 166 associated with the first lateral element row 236 adjacent to the leading edge 156 of the screed plate 136 can have element heights 178 in the vertical direction 135 that are larger than the element heights 178 of the protruding elements 166 in the second lateral element row 238. The vertical dimension of the screed plate 136 therefore gradually reduces in the vertical direction 135 as the textured pattern 164 extends between the forward leading edge 156 and the rearward trailing edge 158 due to the successive changes of element heights 178 of the protruding elements 166.

To further improve the appearance of the paving mat 106 produced by the screed plate 136, the textured pattern 164 can include a lateral leveling band 262 that is located adjacent to the trailing edge 158 of the lower textured surface 152. The lateral leveling band 262 may be the continued progression of the textured pattern 164 in which the sizes and vertical height 178 of the protruding elements 166 decreases between the forward leading edge 156 and the rearward trailing edge 158 of the screed plate 136. The lateral leveling band 262 can be characterized by the absence of protruding elements 166 and channeling grooves 168, and thus has a flat planar configuration. The lateral leveling band 262 can occupy the remaining 15% to 33%, and particularly the remaining 20%, of the length of the lowered textured surface 152 in the travel direction 108 of the screed plate 136. The vertical flatness of the lateral leveling band 262 may function to further compact and smooth out the paving material moving underneath the screed plate 136.

It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

The use of the terms “a” and “an” and “the” and “at least one” or the term “one or more,” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B” or one or more of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context.

Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.