Mobile applicator for thermo pavement marking

• US 8,992,120 B2
• Filed: 01/19/2012
• Issued: 03/31/2015
• Est. Priority Date: 01/19/2011
• Status: Active Grant

• Current Assignee: Graco Minnesota Incorporated (Graco Incorporated)
• Original Assignee: Graco Minnesota Incorporated (Graco Incorporated)
• Inventors: Fredrickson, Steven H., Mattson, Barry W., Lins, Christopher A., Schroeder, James C., Bedard, Roland M., Triplett, Thomas L.
• Primary Examiner(s): HARTMANN, GARY S
• Application Number:
  US13/980,254
• Publication Number:
  US 20130302091A1
• Time in Patent Office: 1,167 Days
• Field of Search: 404/95, 404/111, 404/107
• US Class Current: 404/95
• CPC Class Codes: E01C 23/16 Devices for marking-out, applying, or forming traffic or like markings on finished paving E01C23/14 takes precedence; inserting or forming in not-yet hardened paving E01C23/02, in recesses formed in fully-set paving E01C23/09; marking-out playing courts or playgrounds A63C19/06; applying liquids or other fluent materials to surfaces in general B05; road surface markings per se E01F9/50; Protecting fresh markings
• CPC Class Codes: E01C 23/206 by applying fusible particulate material to the surface, e.g. by means of a gaseous stream
• CPC Class Codes: G06F 2119/18 Manufacturability analysis or optimisation for manufacturability
• CPC Class Codes: G06F 30/398 Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] optical proximity correction [OPC] design processes G03F1/36
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A mobile thermoplastic applicator comprises a kettle, a main gas burner, a heat exchanger plenum, and a screed die box. The kettle has walls which define an interior space for melting thermoplastic. The main gas burner is situated beneath the kettle, and is configured to heat the kettle. The heat exchanger plenum is situated inside the thermoplastic kettle and is configured to subdivide the interior space and circulate heated air from the main gas burner. The screed die box is configured to receive molten thermoplastic from the kettle and deposit that molten thermoplastic on a surface.

Claims

1. A mobile thermoplastic applicator comprising:

a kettle having walls which define an interior space for melting thermoplastic;

a main gas burner situated beneath the kettle to heat the kettle;

a heat exchanger plenum situated inside the kettle and configured to subdivide the interior space into a plurality of distinct but fluidly connected sections and circulate heated air from the main gas burner; and

a screed die box configured to receive molten thermoplastic from the kettle, and to deposit molten thermoplastic on a surface.

2. The mobile thermoplastic applicator of claim 1, wherein the walls of the kettle are hollow, and serve as additional heat exchanger plenums which receive heated air from the main gas burner, and transfer heat into the interior space.

3. The mobile thermoplastic applicator of claim 1, further comprising an agitator moveable within the interior space to break down thermal boundaries in melting thermoplastic via radial, axial, and circumferential shearing.

4. The mobile applicator of claim 3, wherein the agitator is anchored to a rotatable shaft, and comprises a plurality of parallel blades angled obliquely relative to the rotatable shaft.

5. The mobile applicator of claim 4, wherein at least some of the plurality of parallel blades have holes which act as shearing edges for the parallel blades.

6. The mobile thermoplastic applicator of claim 1, further comprising an insulated baffle situated between the main gas burner and the kettle.

7. The mobile thermoplastic applicator of claim 6, wherein the insulated baffle is ceramic fiber blanket clamped to the kettle via a rigid mesh or grate affixed to a bottom portion of the kettle.

8. The mobile thermoplastic applicator of claim 1, further comprising a gas system configured to supply the main gas burner with combustible gas, and having an automatic gas safety valve configured to provide combustible gas to the main gas burner via a gas flow path which is normally closed, and which opens only in response to a voltage received by the automatic gas safety valve.

9. The mobile thermoplastic applicator of claim 8, wherein the voltage is provided by a thermopile situated near a pilot burner, such that the gas flow path opens only when the pilot burner is lit and heating the thermopile.

10. The mobile thermoplastic applicator of claim 8, further comprising a temperature control electrical circuit which interrupts the electric voltage when at least one threshold temperature is exceeded at the kettle, thereby closing the gas flow path.

11. The mobile thermoplastic applicator of claim 1, wherein the heat exchanger plenum is interrupted by a fluid passage connecting the plurality of distinct but fluidly connected sections.

20. The mobile thermoplastic applicator of claim 11, wherein the fluid passage is situated at a bottommost location of the kettle, over the burner.

12. A mobile thermoplastic applicator comprising:

a load bearing frame on wheels;

a kettle mounted on the load bearing frame, and having hollow walls which define an interior space for melting thermoplastic;

a heat exchanger plenum situated inside the kettle and configured to subdivide the interior space into a plurality of distinct but fluidly connected sections;

a main gas burner mounted on the load bearing frame beneath the kettle to heat the kettle, and to heat air which circulates through the heat exchanger plenum and the hollow walls of the kettle;

an agitator rotatably attached between the heat exchanger and the hollow walls of the kettle, and capable of being swept through the interior space to break down thermal boundaries in melting thermoplastic via radial, axial, and circumferential shearing;

an insulated baffle situated between the main gas burner and the kettle;

a gas system supplying the main gas burner with combustible gas, and having an automatic gas safety valve; and

a screed die box configured to receive molten thermoplastic from the kettle, and deposit molten thermoplastic on a surface.

13. The mobile thermoplastic applicator of claim 12, wherein the automatic gas safety valve is configured to provide combustible gas to the main gas burner via a gas flow path which is normally closed, and which opens only in response to a voltage received by the automatic gas safety valve.

14. The mobile thermoplastic applicator of claim 13, wherein the voltage is provided by a thermopile situated near a pilot burner, such that the gas flow path opens only when the pilot burner is lit and heating the thermopile.

15. The mobile thermoplastic applicator of claim 13, further comprising a temperature controller which interrupts the voltage when a temperature at the kettle exceeds an operator-set threshold temperature.

16. The mobile thermoplastic applicator of claim 13, further comprising an over-temperature switch which interrupts the electric voltage when a temperature at the kettle exceeds a threshold temperature preset at the time of manufacture of the thermoplastic applicator.

17. The mobile thermoplastic applicator of claim 12, further comprising a chute configured to carry molten thermoplastic from the kettle to the screed die box.

18. The mobile thermoplastic applicator of claim 12, wherein the kettle is formed substantially of aluminum.

19. The mobile thermoplastic applicator of claim 12, further comprising a lid having a metal spring steel which interfaces with the kettle, such that the lid and the hollow walls of the of the kettle enclose the interior space.