Paving machine with mixing device and discharge conveyor assembly for remixing segregated paving materials

• US 5,533,829 A
• Filed: 05/02/1995
• Issued: 07/09/1996
• Est. Priority Date: 09/29/1994
• Status: Expired due to Term

• Current Assignee: Roadtec Incorporated
• Original Assignee: Astec Industries Incorporated (Johnson Crushers International)
• Inventors: Campbell, Thomas R.
• Primary Examiner(s): Bagnell, David J.
• Assistant Examiner(s): LISEHORA, JAMES
• Application Number:
  US08/433,863
• Time in Patent Office: 434 Days
• Field of Search: 404/75, 404/101, 404/108, 404/110, 404/113, 404/72, 404/81
• US Class Current: 404/81
• CPC Class Codes: E01C 19/174 Apparatus with pump-discharge
• CPC Class Codes: E01C 19/405 with spreading-out, levelling or smoothing means other than the tamping or vibrating means for compacting or smoothing, e.g. with screws for spreading-out the previously dumped material, with non-vibratory lengthwise reciprocated smoothing beam E01C19/407 takes precedence
• CPC Class Codes: E01C 19/48 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 E01C19/002, E01C23/065 take precedence; devices for guiding or controlling the machines along a predetermined path E01C19/004
• CPC Class Codes: E01C 19/4853 Apparatus designed for railless operation, e.g. crawler-mounted, provided with portable trackway arrangements
• CPC Class Codes: E01C 2301/10 Heated screeds
• CPC Class Codes: E01C 2301/30 Cabin details

Abstract

A paving machine is described which includes: a gravity feed hopper located near a front end of a chassis; a distributing auger mounted on the chassis near the rear end thereof and extending transversely across the chassis; a remixing device including a variable-pitch screw auger with i) a first flight section and ii) a second flight section, the second flight section being located transversely between a lower discharge opening of the hopper and the first flight section, the pitch of the first flight section being lower than the pitch of the second flight section so that volumes bounded by flights of the second flight section are greater than volumes bounded by flights of the first flight section, so as to enable finer paving materials, located in a transverse central portion of the hopper to enter void spaces in volumes bounded by flights of the second flight section and combine with coarser paving material, thereby remixing segregated paving materials; and a discharge conveyor assembly extending longitudinally and horizontally from the lower discharge opening to the distributing auger, the discharge conveyor assembly including a pair of parallel drag slat conveyors, each of the pair of parallel drag slat conveyors including a discharge end located directly above the distributing auger for discharging paving materials directly on top of the distributing auger, thereby remixing segregated paving materials. The remixing device and the discharge ends provide significant advantages in that they both remix segregated paving materials.

Claims

1. A paving machine comprising:

A. a portable chassis having front and rear ends;

B. a gravity feed hopper located near the front end of said chassis, said gravity feed hopper having (1) an upper inlet, (2) front and rear walls, (3) side walls, (4) a transverse central portion and (5) a floor connecting said front and rear walls to one another and having a lower discharge opening formed therein at a location between said front and rear walls;

C. a distributing auger mounted on said chassis near said rear end thereof and extending transversely across said chassis, for remixing segregated paving materials and distributing paving materials immediately adjacent a previously paved road segment;

D. a remixing device which conveys paving materials transversely from said side walls toward said lower discharge opening while remixing said materials, said remixing device including a variable-pitch screw auger with i) a first flight section and ii) a second flight section, said second flight section being located transversely between said lower discharge opening and said first flight section, the pitch of said first flight section being lower than the pitch of said second flight section so that volumes bounded by flights of said second flight section are greater than volumes bounded by flights of said first flight section, so as to enable finer paving materials, located in said transverse central portion to enter void spaces in volumes bounded by flights of said second flight section and combine with coarser paving material, thereby remixing segregated paving materials; and

E. a discharge conveyor assembly extending longitudinally and horizontally from said lower discharge opening of said gravity feed hopper to said distributing auger, said discharge conveyor assembly including a pair of parallel drag slat conveyors, each of said pair of parallel drag slat conveyors including a discharge end located directly above said distributing auger for discharging paving materials directly on top of said distributing auger, thereby remixing segregated paving materials.

2. A paving machine as defined in claim 1, wherein said front and rear walls are inclined inwardly at lower ends thereof towards said discharge opening.

3. A paving machine as defined in claim 1, wherein said discharge opening of said gravity feed hopper extends less than 1/2 the transverse length of said gravity feed hopper.

4. A paving machine as defined in claim 1, wherein said front wall of said gravity feed hopper has an enlarged notch formed in an upper end thereof for receiving a material transfer device.

5. A paving machine comprising:

A. a portable chassis having front and rear ends;

B. a gravity feed hopper located near the front end of said chassis, said gravity feed hopper having (1) an upper inlet, (2) front and rear walls, (3) side walls, (4) a transverse central portion and (5) a concave floor connecting said front and rear walls to one another and having a lower discharge opening formed therein, each of said front and rear walls having a lower portion inclined towards said discharge opening;

C. a variable-pitch screw auger which extends transversely across said gravity feed hopper and which conveys paving materials transversely from said side walls toward said lower discharge opening, said variable-pitch screw auger having i) a first flight section and ii) a second flight section, said second flight section being located transversely between said discharge opening and said first flight section, the pitch of said first flight section being lower than the pitch of said second flight section so that volumes bounded by flights of said second flight section are greater than volumes bounded by flights of said first flight section, so as to enable finer paving materials, located in said transverse central portion to enter void spaces in volumes bounded by flights of said second flight section and combine with coarser paving material, thereby remixing segregated paving materials;

D. a distributing auger, mounted on said chassis near said rear end thereof and extending transversely across said chassis, for remixing segregated paving materials and distributing paving materials immediately adjacent a previously paved road segment; and

E. first and second parallel drag slat conveyors extending longitudinally and horizontally from said lower discharge opening of said gravity feed hopper to said distributing auger, each of said first and second parallel drag slat conveyors having a discharge end located directly above said distributing auger for discharging paving materials directly on top of said distributing auger, thereby remixing segregated paving materials,

wherein said discharge opening extends less than 1/2 the transverse length of said gravity feed hopper and said front wall of said gravity feed hopper has an enlarged notch formed in an upper end thereof for receiving a material transfer device.

6. A method comprising:

A. providing a paving machine with

1. a portable chassis having front and rear ends;

2. a gravity feed hopper located near the front end of said chassis, said gravity feed hopper having (a) an upper inlet, (b) front and rear walls, (c) side walls, (d) a transverse central portion and (e) a floor connecting said front and rear walls to one another and having a lower discharge opening formed therein at a location between said front and rear walls;

3. a variable-pitch screw auger which extends transversely across said gravity feed hopper and which conveys paving materials transversely from said side walls toward said lower discharge opening, said variable-pitch screw auger having i) a first flight section and ii) a second flight section, said second flight section being located transversely between said lower discharge opening and said first flight section, the pitch of said first flight section being lower than the pitch of said second flight section so that volumes bounded by flights of said second flight section are greater than volumes bounded by flights of said first flight section, so as to enable finer paving materials, located in said transverse central portion to enter void spaces in volumes bounded by flights of said second flight section and combine with coarser paving material, thereby remixing segregated paving materials;

4. a distributing auger, mounted on said chassis near said rear end thereof and extending transversely across said chassis, for remixing segregated paving materials and distributing paving materials immediately adjacent a previously paved road segment; and

5. a discharge conveyor assembly extending longitudinally and horizontally from said lower discharge opening of said gravity feed hopper to said distributing auger, said discharge conveyor assembly including a pair of parallel drag slat conveyors, each of said pair of parallel drag slat conveyors including a discharge end located directly above said distributing auger for discharging paving materials directly on top of said distributing auger, thereby remixing segregated paving materials;

B. storing paving materials in said gravity feed hopper;

C. feeding said paving materials transversely to said lower discharge opening while remixing segregated paving materials, said feeding and remixing including rotating said variable-pitch screw auger so as to remix segregated paving materials;

D. discharging said paving materials from said lower discharge opening to said discharge conveyor assembly;

E. conveying said paving materials along said pair of parallel drag slat conveyors until said paving materials reach the discharge ends of said pair of parallel drag slat conveyors;

F. discharging said paving materials from said discharge ends of said drag slat conveyors directly on top of said distributing auger so as to remix segregated paving materials; and

G. distributing said paving materials onto a surface to be paved using said distributing auger.

7. A method as defined in claim 6, wherein said distributing auger is positioned closely adjacent to an end of a previously-paved surface segment, and further comprising propelling said chassis forwardly away from said previously-paved segment during said discharging and distributing steps.

8. A method as defined in claim 7, wherein said distributing step comprises distributing said paving materials closely adjacent said previously-paved segment.

9. A method as defined in claim 6, wherein substantially all of said paving materials are remixed during said feeding and distributing steps.

10. A method as defined in claim 6, further comprising working said paving materials into a mat after said distributing step using a screed mounted on said chassis.