Patent Publication Number: US-10323363-B1

Title: Angled main screed for improved material flow

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to a main screed included in a rear mount screed assembly and, more particularly, to a main screed, included in a rear mount screed assembly, that has angled end faces in order to provide improved material flow at or near ends of the main screed. 
     BACKGROUND 
     A paving machine can be used in the laying of bituminous roadway mat. The typical paving machine employs a screed assembly (sometimes referred to as a floating screed) for spreading and compressing a bituminous material to form a smooth surfaced roadway mat. The screed assembly typically has a set of screed extensions, slidingly attached to a main body of the screed assembly (herein referred to as a main screed), that allow an operator to control and % or select a width of the screed assembly. These screed extensions are typically connected to a linear power source (e.g., a bi-directional hydraulic cylinder or other similar activator), which is selectively operable in response to controls disposed at an operator control station. This permits the operator to control the position of the screed extensions in response to changing requirements as the paving machine progresses. For example, this permits the operator to accommodate obstacles in the path of the paving machine (e.g., sewer drains, manhole covers, and/or the like) and also permits overwidth paving of the road surface to accommodate roadway features (e.g., driveway entrances, tie-ins, and/or the like). The screed assembly can be a rear mount screed assembly (i.e., a screed assembly in which the screed extensions are mounted behind the main screed relative to the direction of travel of the paving machine) or a front mount screed assembly (i.e., a screed assembly in which the screed extensions are mounted in front of the main screed relative to the direction of travel of the paving machine). 
     The paving machine typically includes a storage means for receiving and containing a discreet quantity of loose bituminous aggregate material, and a material flow means for conveying the bituminous aggregate material to the roadbed. The loose material is then displaced laterally in front of the screed assembly. As the paving machine progresses along the roadbed, the screed assembly engages the loose material, plowing under and compressing the material into the desired roadway mat. Typically, endgates are provided on outer, distal ends of the screed extensions in order to ensure that the material disposed in front of the screed extensions is not shunted aside, beyond the width of the screed assembly. In some cases, means for providing the lateral disposition of the material is a flighted auger providing two oppositely directed flights from a centerline of the paving machine (e.g., in order to provide disposition of an equal amount of material toward each outer edge of the screed assembly). However, the arrangement of the main screed and the screed extensions can introduce material segregation and/or material flow issues that can negatively impact a quality of the roadway mat leveled by the screed assembly. 
     One attempt to address one such issue, “streaking” in the roadway mat, is disclosed in U.S. Pat. No. 6,106,192 that issued to Blaw-Knox Construction Equipment Corp. on Aug. 22, 2000 (“the &#39;192 patent”). Per the &#39;192 patent, streaking occurs when a section of the roadway mat appears brighter in appearance or “shinier” than other portions of the roadway mat, and occurs in sections of the roadway mat that are leveled by a region of a front mount screed assembly at transitions from inner ends of the screed extensions to outer ends of a main screed. The &#39;192 patent postulates that streaking occurs due to fine particles of the material tending to accumulate at the inner ends of the screed extensions (such that the streaked sections are formed with a higher concentration of fine-grained material), and/or due to the outer sections of the roadway mat being leveled by the screed extensions prior to an inner section being leveled by the main screed. The &#39;192 patent discloses a flow modifying device, for use in a front mount screed assembly, that includes a deflector member connected with a screed extension and having a flow surface facing toward a central axis of a main screed. Per the &#39;192 patent, the flow surface is contactable with paving material and is configured to displace the material toward the central axis when the paving machine moves in the intended travel direction. 
     While the flow modifying device of the &#39;192 patent is aimed to address streaking caused by use of a front mount screed, the flow modifying device does not address material segregation and/or material flow issues seen with the use of a rear mount screed assembly. For example, in a rear mount screed, the main screed has a sharp (e.g., 90 degree, square, perpendicular, and/or the like) corner and end face at ends of the main screed. In operation, as material flows around and/or near these sharp corners of the main screed, the material may be pinched between an end face of the main screed and an endgate of the screed extension. Such pinching can result in increased wear on a component of the rear mount screed assembly (e.g., the end face of the main screed, the endgate, and/or the like) and/or material segregation at or near the corner of the main screed. Further, when the screed extension is retracted from an extended position (e.g., due to a change in a desired width of the roadway mat), the retraction of the rear mount screed assembly can be impeded when, for example, the material is compressed between the end face and the endgate such that the screed extension binds, stalls, and/or is otherwise rendered unable to retract to a desired position. 
     The main screed with angled end faces of the present disclosure can be used in a rear mount screed assembly in order to solve one or more of the problems set forth above and/or other problems in the art. 
     SUMMARY 
     In one aspect, the present disclosure is related to a paving machine including a rear mount screed assembly including a main screed and a screed extension, the main screed including a front face and an angled end face, wherein an angle between a plane of the front face of the main screed and a plane of the angled end face of the main screed is less than 90 degrees, and the screed extension being behind the main screed relative to a direction in which the paving machine is to travel during operation. 
     In another aspect, the present disclosure is related to a rear mount screed assembly including a main screed comprising a front face and an angled end face, wherein an angle between a plane of the front face of the main screed and a plane of the angled end face of the main screed is less than 90 degrees; and a screed extension arranged behind the main screed relative to a direction in which the rear mount screed assembly is to be moved during operation. 
     In yet another aspect, the present disclosure is related to a screed assembly including a main screed and a screed extension, wherein the main screed includes a front face and an end face, wherein the end face is angled such that the end face is non-perpendicular to the front face of the main screed, and wherein the screed extension is arranged behind the main screed relative to a direction in which the screed assembly is to be moved during operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an example paving machine that includes a rear mount screed assembly; 
         FIG. 2  is a diagram of an example rear mount screed assembly, including a main screed with angled end faces, that may be used in the paving machine of  FIG. 1 ; 
         FIG. 3  is a diagram of an example implementation of an angled end face of a main screed; and 
         FIG. 4  is a diagram of another example implementation of an angled end face of a main screed. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates to a main screed, included in a rear mount screed assembly, that has angled end faces in order to improve material flow. The main screed with the angled end faces (herein referred to as an angled main screed) has universal applicability to any machine utilizing a rear mount screed. The term “machine” may refer to any machine that performs an operation associated with an industry, such as, paving, mining, construction, farming, transportation, or any other industry. 
       FIG. 1  is a diagram of an example paving machine  10  that includes a rear mount screed assembly  40 . As shown, paving machine  10  may include a frame  12  that is supported by and transported upon a plurality of transport wheels  14  oppositely disposed on axles  16  that extend underneath frame  12  transverse to a direction of motion of paving machine  10 . A hopper  20  may be disposed on a forward portion of frame  12 . Hopper  20  may include sides  22  extending vertically from frame  12  so that hopper  20  can receive material (e.g., a fume-emitting bituminous aggregate material, such as asphalt) from a transport vehicle (e.g., a dump truck), and retain the material in hopper  20  pending disposition of the material on a surface to be paved by paving machine  10 . 
     As shown, towards a rear of the frame  12 , an operator station  24  may be provided so that an operator seated at a chair  26  can control operation of paving machine  10  by way of controls provided on a control panel  28 . Also disposed toward the rear of the frame  12  may be an engine housing  30  on which is provided an exhaust stack  32  for exhausting combustion by-products of engine housing  30 . As further shown, a walkway area  34  may be provided between hopper  20  and engine housing  30  in order to permit access by personnel (e.g., the operator, members of a paving crew, and/or the like) across paving machine  10 , to engine housing  30 , or to other machinery and components that may be disposed or mounted upon the paving machine  10 . 
     As further shown in  FIG. 1 , a rear mount screed assembly  40  may be (e.g., pivotally) connected to frame  12  by a set of screed support arms  42 . In some cases, the set of screed support arms  42  may be substantially parallel and horizontal to one another, being disposed along frame  12  and pivotally connected to frame  12  at arm pivot  44 , which has a horizontal axis transverse to the direction of travel of paving machine  10 , thus permitting vertical movement of rear mount screed assembly  40 . While not shown, paving machine  10  may include a means by which vertical movement of rear mount screed assembly  40  is limited and/or controlled. Rear mount screed assembly  40  as shown is comprised of a main screed  46  and screed extensions  48  which are disposed behind and approximately parallel to main screed  46 . In some implementations, main screed  46  may have angled end faces  47 , as shown and described below in association with  FIG. 2 . In some implementations, screed extensions  48  may include endgates  49  mounted there, as shown and described below in association with  FIG. 2 . 
     As further shown, paving machine  10  may further include an aggregate disposition means  50 . Aggregate disposition means  50  may include an auger  52  (e.g., a flighted auger) disposed adjacent a rear of frame  12  in an approximate horizontal and axially transverse position with respect to the direction of travel of paving machine  10 . As further shown, an auger support means  54  may be arranged for controlling a position of aggregate disposition means  50 . 
     As indicated above,  FIG. 1  is provided as an example. Other examples are possible and may differ from what was described in connection with  FIG. 1 . In other words, paving machine  10 , the components shown as being included in paving machine  10 , and the arrangement of these components, are provided for illustrative purposes only. Also,  FIG. 1  does not illustrate scale representations of paving machine  10  and/or the components shown as being included in paving machine  10 . Rather, paving machine  10 , as described herein is not intended to be limiting, but is intended to be illustrative of apparatus and applications in which the present invention may be employed. For example, although paving machine  10  is described as a wheel-type paver, the implementations described herein may be equally suitably employed on a track-type paver. 
       FIG. 2  is a diagram of a top view of an example rear mount screed assembly  40 , including main screed  46  with angled end faces  47 , that may be used in paving machine  10 . For purposes of clarity, some components shown and described in association with  FIG. 1  are omitted from  FIG. 2 . 
     As described above, paving machine  10  may operate on and along a prepared roadbed surface  60  with hopper  20  facing the direction of travel so as to receive and contain a material. With reference to  FIG. 2 , a quantity of the material may be deposited (e.g., at a selected volumetric flow rate) from paving machine  10  in a section of material reservoir  62  preceding main screed  46 . Aggregate disposition means  50  (e.g., auger  52 ) may operate to move a portion of the material toward ends of main screed  46  (e.g., away from a center of main screed  46 ) such that the material flows toward an area of material reservoir  62  preceding screed extension  48 . A position of each screed extension  48  may be variable, and may be selected (e.g., by the operator) to be at a position between a minimum extension E 1  and a maximum extension E 2  such that the coverage area of material reservoir  62  can be varied. The position of each screed extension  48  may be independent (e.g., such that each screed extension  48  may be independently extended to a different length). 
     As shown in  FIG. 2 , main screed  46  may include end faces  47  that are angled with respect to a front face  51  such that an angle α (e.g., an angle from a plane of front face  51  to a plane of angled end face  47 ) is less than 90 degrees. In other words, main screed  46  may include end faces  47  that are angled such that main screed  46  does not include a sharp (e.g., 90 degree, square, and/or the like) corner between an end face and front face, as is the case with typical main screeds. Put another way, main screed  46  may include an end face  47  that is non-perpendicular to front face  51  of main screed  46 . In some implementations, angle α may be any angle that is less than 90 degrees (e.g., 75 degrees, 60 degrees, 45 degrees, 30 degrees, 15 degrees, and/or the like). In some implementations, the angle α may be in a range from approximately 60 degrees to approximately 30 degrees, from approximately 75 degrees to approximately 15 degrees, and/or the like. 
     In some implementations, as indicated in  FIG. 2 , angles between end faces  47  and front face  51  may be approximately equal to one another (e.g., the angled end faces  47  may have the angle α relative to front face  51  or may match within a threshold amount). Alternatively, end faces  47  may be differently angled relative to front face  51 , in some implementations. 
     With reference to  FIGS. 3 and 4 , in some implementations, the angled end face  47  may be formed by a screed plate  46 - 1  of main screed  46  (e.g., the screed plate  46 - 1  may be an angled screed plate). Additionally, or alternatively, the angled end face  47  may be formed by an end cap  46 - 2  of main screed  46  (e.g., the end cap  46 - 2  may be an angled end cap). In some implementations, the angled end face  47  may be formed by both the screed plate  46 - 1  and the end cap  46 - 2  of main screed  46 . 
       FIG. 3  is a diagram illustrating an example main screed  46  in which angled end face  47  is formed by an angled screed plate  46 - 1  (outlined by dashed lines on the bottom of main screed  46  in  FIG. 3 ) and an angled end cap  46 - 2  (a left-most face of main screed  46  in  FIG. 3 ). As shown in  FIG. 3 , in this example, both the screed plate  46 - 1  and the end cap  46 - 2  are angled in order to form angled end face  47 . 
       FIG. 4  is a diagram illustrating an example main screed  46  in which angled end face  47  is formed by an angled end cap  46 - 2  (a left-most face of main screed  46  in  FIG. 4 ), while screed plate  46 - 1  has a squared corner. As shown in  FIG. 4 , in this example, only end cap  46 - 2  forms angled end face  47 . As shown, screed plate  46 - 1  may be formed in order to permit formation of angled end face  47  by end cap  46 - 2  only. 
     In some implementations, the angled end faces  47  of main screed  46  improve material flow around and/or near the angled corner of main screed  46  during operation of paving machine  10 , as described below. 
     As indicated above,  FIG. 2  is provided as an example. Other examples are possible and may differ from what was described in connection with  FIG. 2 . In other words, the number and arrangement of components shown for rear mount screed assembly  40  are provided for illustrative purposes only, and  FIG. 2  does not illustrate scale representations of rear mount screed assembly  40  or components of rear mount screed assembly  40 . Rather, rear mount screed assembly  40 , as described herein is not intended to be limiting, but is intended to be illustrative of apparatus and applications in which implementations described herein may be employed. 
     INDUSTRIAL APPLICABILITY 
     The disclosed main screed with angled end faces may be used with any rear mount screed in which improved material flow and/or reduced component wear is desired, such as a paving machine  10 . 
     In operation, an angled corner of main screed  46  (a corner of main screed  46  that is formed by an angled end face  47  and front face  51 ) improves material flow (e.g., as compared to a main screed including a sharp corner) by providing a comparatively more natural pathway for material flow. This more natural material flow may reduce material pinching between the angled end face  47  and endgate  49 , meaning that component wear and/or material segregation at or near the angled corner of main screed  46  is also reduced (e.g., as compared to a main screed including a sharp corner). Further, due to the reduced material pinching afforded by the improved material flow at or near the angled corner of main screed  46 , a likelihood that screed extension  48  will bind, stall, and/or otherwise be rendered unable to retract to a desired position is reduced (e.g., since, during retraction, the improved material flow may alleviate material compression between endgate  49  and angled end face  47 ). 
     In other words, the disclosed main screed  46  with angled end faces  47  provides a number of advantages, such as improved material flow at or near an angled corner of main screed  46 , reduced material segregation at or near the angled corner of main screed  46 , reduced component wear associated with one or more components of rear mount screed assembly  40 , a reduced likelihood of binding, stalling, and/or the like, during retraction of screed extension  48 , any of which can improve quality of a surface paved using paving machine  10 . 
     As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Also, as used herein, the terms “has,” “have.” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on.” 
     The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementations. It is intended that the specification be considered as an example only, with a true scope of the disclosure being indicated by the following claims and their equivalents. Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of possible implementations. Although each dependent claim listed below may directly depend on only one claim, the disclosure of possible implementations includes each dependent claim in combination with every other claim in the claim set.