Patent Application
20130105078
Raised road studs are used to mark roads. Raised road studs provide a reflective indicator increasing the visibility of the marker to a driver. They may be secured to a road surface using an adhesive material that must be melted before it is applied. It then hardens as it cures, and cements the stud to the roadway. The adhesive may be from tar, asphalt, bitumen, and similar substances, as well as mixtures of these. The molten adhesive must be applied hot, so that a road stud can be placed on the adhesive, and the adhesive will cool and set and adhere the road stud to the road surface. The adhesive is heated in boilers that are typically a half ton in size. The boilers are heated using a gas burner and an open flame, and it may take approximately one hour to heat the adhesive to the appropriate temperature. Moreover, the boilers maintain the adhesive at its melting temperature as long as road studs are being applied to mark a road. Traffic safety workers manually apply the molten adhesive by and manually secure a road stud to the road surface. Some road stud marking jobs may require the hand application of hundreds of road studs. Often, the traffic safety workers perform this task near live lanes of traffic.
One exemplary embodiment of a road stud placement and removal apparatus comprises an induction heating system for heating a quantity of roadway adhesive for application to a road surface. The embodiment also comprises an applicator for depositing a predetermined quantity of adhesive to the roadway surface. A specific volume of the road adhesive may be dispensed by the system on the road surface, and a road stud placement assembly may automatically place a road stud in the dispensed adhesive. The stud placement system is operable to automatically dispense stud adhesive and place road studs in succession. According to certain embodiments, the placement system may be supported by a vehicle, which enables automatic placement of roadway studs at predefined intervals as the vehicle moves.
According to another exemplary embodiment, a road marker or stud placement apparatus and an apparatus for removing studs from the roadway surface are mounted to the same vehicle. Thus, previously applied studs maybe removed prior to placement of new studs. For one example, the stud removal apparatus comprises a scraper blade for separating a previously applied and fixed road stud from the road surface. The separated road stud may be directed by a rotating brush or other mechanism for sweeping the stud toward and onto a conveyor carried by the vehicle or other means for transporting the separated road stud to a holding or storage container.
An induction heating system according to embodiments of the present disclosure may be used to heat any material used in road marking For example, the induction heating system may be used to heat a marking thermoplastic material so it can be applied to a road surface. The induction heating system may also be used to heat air from a compressed air source. This air may be emitted to dry the road surface before the thermoplastic is applied.
In the following description of a road stud placement and removal system, like numbers refer to like parts.
Moreover, heating and melting stud adhesive and other material with induction heating as described further below eliminates the need to have a naked flame associated with propane gas or oil burners used to heat the boilers. Heating only the required amount of material in an induction heating system may increase the efficiency, reduce the waste, and reduce the pollution associated with conventional road marking techniques and equipment. In addition, the material may be heated and melted as needed, thereby eliminating the energy and equipment needed to maintain the elevated temperature throughout the process of marking a substantial portion of a roadway.
The road stud placement and removal system 10 shown in
Conventional boiling for melting solid bitumen and similar adhesives is replaced with an induction heating system 20. Using induction heating, the cold block of solid adhesive 26 may be heated up in approximately 30 seconds as opposed to conventional techniques which require a boiler and an hour or more to heat the adhesive to its melting point. The induction heating system 20 may be electrically coupled to a high frequency electric power supply 25, which may be located on the vehicle 18. The high frequency power supply is, in this example, comprised of a diesel powered generator for generating current that is pushed through a switching circuit in order to generate a high frequency current for inducing heating of adhesive when placed within a crucible in which blocks of adhesive have been placed. Induction heating using the current from the power supply 25 heats the roadway adhesive to a melting temperature relatively more quickly than conventional boilers. Less adhesive can be melted shortly before use, reducing the need to melt large quantities of it in advance.
In operation, the road stud placement and removal system 10 is adapted for being driven on a vehicle 18 to the location where studs are to be placed or replaced. The illustrated vehicle 18 is an example of a heavy duty traffic safety vehicle. In this example, the stud placement and removal system is placed on the bed of a truck. Examples of other vehicles for transporting system 10 include trailers and combinations of trailers with tractors and other types of vehicles. In another exemplary embodiment, the system 10 is placed on a trailer pulled by a motor vehicle or tractor, the combination of which is considered to be a vehicle 18. Embodiments of the present disclosure may incorporate any appropriately sized vehicle.
In the illustrated example, the stud placement assembly 14 and the stud removal assembly 16 are each adapted to be moved between a stowed position and an operational position. During transportation, the stud placement assembly 14 and the stud removal assembly 16 may be retracted into their respective stowed positions 22 and 24 in which they are raised. Optionally, one or both assemblies may also be shifted inboard. Once the vehicle 18 is at the appropriate location, the stud placement assembly 14 and/or the stud removal assembly 16 are deployed to their operational positions as shown in
The induction heating occurs when the power supply 25 supplies a current through the coil 30. The coil may be a copper pipe, wire, or other suitable material known in the art to carry a current for induction heating. The coils 30 carry a high frequency, alternating electric current through the coil 30 that is wrapped around the crucible 28. The crucible may be a generally cylindrical conductor that can be heated through the induction heating method. In certain embodiments, the crucible 28 may be formed from steel or another type of metal. The alternating electric current passing through the coil 30 generates a magnetic field in the vicinity of the crucible 28. The magnetic field creates currents in the crucible 28. These currents flow in opposite directions through the crucible 28. The resistance of the currents flowing in opposite directions in the crucible 28 causes the crucible 28 to heat. The coils 30 may remain cool. By heating the crucible 28 using this induction heating method, the crucible 28 may be heated to a point where the adhesive block 26 reaches its melting temperature. This may be a quick method of heating the crucible 28 and allowing the adhesive block 26 to reach its melting temperature. It may be much faster than the conventional method of heating the adhesive block in a boiler and having to maintain the elevated temperature of the boiler to keep the adhesive molten so that it may be applied to the road surface. A measured amount of the molten adhesive or bitumen 34 may be dispensed by the dispenser nozzle 32 onto the road surface. A road stud 12 may be pressed into the dispensed molten adhesive 34 and once cured, cement the road stud 12 to the road surface.
The stud placement assembly 14 also includes the stud applicator assembly 40. The stud applicator assembly 40 includes a stud magazine 42 and a stud placement cylinder 36. Once the molten adhesive 34 is dispensed on the road surface, the assembly 14 may translate such that a stud gripper 38 is positioned over the molten adhesive 34. The stud gripper 38 may receive a road stud 12 from the stud magazine 42 and retain the stud 12 in its gripper jaws. Once in this position, the stud placement cylinder 36 may cause the stud gripper 38 to descend towards the molten adhesive 34. Once a particular height is reached, the stud placement cylinder 36 may apply appropriate pressure such that the stud 12 seats into the molten adhesive 34. Then, the stud gripper 38 may release the stud, and the stud 12 will remain in the molten adhesive 34. This process of dispensing the molten adhesive 34 and placing the road stud 12 may be repeated as the vehicle 18 moves along the path where the studs are needed. This automatic road stud application may eliminate the dangerous condition of having a worker manually applying adhesive and road studs near live lanes of traffic.
Once a specific volume of adhesive has been dispensed, the induction heating system 20 and the stud applicator 40 may translate linearly such that the stud gripper 38 is positioned over the molten adhesive 34. This position is illustrated in
The components of the stud placement assembly 14 are secured to a transfer carriage 60. Lateral movement of the transfer carriage 60 may be guided by transfer guide rails 64 and may be powered by transfer cylinder 62 similar to the deployment cylinder 52, the transfer cylinder 62 may be a pneumatic cylinder that, when activated, can drive the transfer carriage 60 and the components to which it is coupled laterally a predetermined distance. Transfer bearings 65 may be attached to the transfer carriage and may slide linearly along the transfer guide rails 64.
Prior to or during this translation, an escapement slide 80 may retrieve a stud 12 from the stud magazine 42 and slide the stud 12 so that it is received and secured by the stud gripper 38. In this manner, after the translation, the stud is positioned directly over the molten adhesive 34 such that it may be pressed into the molten adhesive and applied to the road surface.
Once the stud 12 and the stud gripper 38 are positioned over the molten adhesive, the stud placement carriage 70 may be lowered. The lowering of the stud placement carriage may be directed by the stud placement guide rails 74 and may be powered by the stud placement cylinder 72. As with the other drive cylinders, stud placement cylinder 72 may be pneumatically powered to drive the stud placement carriage downward towards the road surface.
The stud placement carriage 70 may include a height gauge wheel 76. As the stud placement carriage 70 is lowered towards the road surface, the first contact made with the surface is by the height gauge wheel 76. This contact may be electrically communicated to the stud placement cylinder 72 indicating that the stud placement carriage has reached a certain known height above the road surface.
To ensure proper pressure is applied such that the stud 12 is properly seated in the molten adhesive 34, a lower section of the stud placement carriage 70 may be free to move in a vertical direction constrained by vertical bar 78 and having a spring 79. This free moving lower carriage and spring 79 may ensure that a proper force is applied to seat the stud 12 into the molten adhesive as shown in
This process can be used to position one stud 12 in one specific volume of molten adhesive 34. This process may be repeated once the vehicle 18 moves a predetermined interim along the required path. In this manner, roadway studs may be automatically positioned and fixed to the road surface without requiring manual application of molten adhesive from a hot boiler and manual positioning and placement of a road stud. In an alternate embodiment, the stud placement assembly 14 may be configured to cement two studs 12 parallel to each other to create a double line roadway marker.
Similar to the induction heating system 20 that was described with respect to the previous embodiments, the air for the heated air stream 112 and the thermoplastic layer 114 may be heated with the induction heating system as described previously with regard to the stud placement assembly 14. To this end, the coils 116 may be copper pipes that carry a high frequency alternating electric current from a power supply 25 that is located on the vehicle 18. The current travels through the coils 116 and in so doing an air heater 120 is heated via induction heating. The air heater may be a cylindrical component made of a conductive material, such as a metal like steel. Air from an air compressor 118 provides the air flow through the air heater 120 where it can be heated to an elevated temperature sufficient to dry a wet road surface. The heated air 112 may be emitted through an air nozzle 122. The air nozzle 122 may be positioned a short distance above the road surface to be dried with the heated air stream 112.
Positioned behind the air nozzle 122 may be a dispenser nozzle 126. The dispenser nozzle 126 may lay a strip of heated thermoplastic 114 on the roadway that was just dried by the heated air stream 112. The thermoplastic 114 may be heated by the induction heating system 115 to a temperature that causes the material to flow. The induction heating system 115 may employ the same coil 116 that wraps around the air heater 120. According to an alternate embodiment, a different coil may be electrically coupled to the power supply 25 and the current from the power supply 25 may travel through the separate coils to create the induction heating in the thermoplastic heater 124. The current may travel through the coil 116 in the direction indicated by the arrows to ensure induction heating of the cylindrical metallic thermoplastic heater 124.
In certain embodiments, the air nozzle 122 and the dispenser nozzle 126 may be protected from rain or road debris by a rain hood 128. According to embodiments of the present disclosure, the induction heating system may be used to heat any type of coating or other material such that it flows and can be applied to a surface.
Heating with the induction heating system 115 may be highly efficient because only the thermoplastic heater 124 and/or the air heater 120 are heated. The coils 116 themselves may not get hot. Also, the induction heating system 115 uses no flames or flammable materials. Moreover, fumes that are associated with conventional thermoplastic road markings may be greatly reduced or eliminated.
The foregoing description is of exemplary and preferred embodiments. The invention, as defined by the appended claims, is not limited to the described embodiments. Alterations and modifications to the disclosed embodiments may be made without departing from the invention. The meaning of the terms used in the claims are, unless expressly stated otherwise, intended to have ordinary and customary meaning and are not intended to be limited to the details of the illustrated structures or the disclosed embodiments.
