Patent Application
20090041542
The current invention relates to milling machines for milling asphalt or concrete in roads, sidewalks, parking lots, or other paved surfaces. While milling and resurfacing a paved surface, the milling machines often encounter metal objects which are covered partially or completely by the paved surface such as manhole covers or railroad tracks. In such circumstances, if the metal object isn't detected beforehand, the object, milling tools on the milling machine, or both may be damaged. In order to avoid this, a metal detector may be used to detect the objects before milling the paved surfaces. It may also be advantageous to know the size and depth of the metal objects. Some inventions of the prior art disclose metal detectors in combination with a pavement resurfacing machine.
U.S. Pat. No. 7,077,601 to Lloyd, which is herein incorporated by reference for all that it contains, discloses a machine for providing hot-in-place recycling and repaving an existing asphalt-based pavement, in which the pavement is first heated.
U.S. Pat. No. 5,786,696 to Weaver et al., which is herein incorporated by reference for all that it contains, discloses a metal detector which utilizes digital signal processing and a microprocessor to process buffers of information which is received at a periodic rate. The metal detector is able to determine the depth of a target by comparing the quadrature phase components received from first and second receive antennas. The size of the target is determined by reference to a look-up table based on the depth factor and the signal amplitude determined for the target object.
A milling machine for milling a paved surface having milling tools connected to an underside of a body of the machine and at least one metal detector attached to a front end of the machine. The metal detector has at least one electrically conductive coil disposed within a magnetically conductive, electrically insulating trough. Electronic equipment is in communication with the metal detector, the equipment being adapted to interpret feedback from the detector.
The machine may comprise at least two metal detectors positioned such that a detection range of a first detector extends farther into the surface than a detection range of a second detector. The machine may comprise at least two metal detectors, each adapted to detect metal objects at different depths. The machine may comprise a plurality of metal detectors arranged in a plurality of arrays, each array positioned at a different distance above the paved surface. The machine may comprise a plurality of metal detectors positioned at different angles. The milling tools may be adapted to be automatically laterally adjusted in a closed-loop system by the electronic equipment in response to feedback from the detector.
The metal detector may comprise at least 2 electrically conductive coils disposed within a magnetically conducting, electrically insulating trough. The metal detector may further comprise a second electrically conductive coil disposed within a second magnetically conducting, electrically insulating trough. The first and second troughs may comprise different diameters and/or depths. The metal detector may be adapted to detect metal objects up to 1 foot deep. The metal detector may be adapted to determine the size of a metal object. The metal detector may be vertically adjustable. The metal detector may be attached to the front end such that during operation the detector is positioned from 0.5 to 8 inches above the paved surface. The metal detector may also be positioned within 8 feet of the milling tools. A detection range of the metal detector may be controlled by a variable voltage source.
The magnetically conducting, electrically insulating trough may comprise ferrite, iron, mu-metals, nickel, or combinations thereof. The magnetically conducting, electrically insulating trough may be segmented. The magnetically conducting, electrically insulating trough may comprise a magnetic permeability of at least 100. The coil may be coated with polyketones, PEEK, or other insulating materials. The coil may be circular, rectangular, straight, triangular, ovular, or any polygonal shape.
Referring now to
The detector 105 may emit a magnetic field which extends into the surface 200. As the detector 105 passes over a metal object 203, the magnetic field may induce a magnetic field in the object 203, depending on the material of the metal object 203. The detector 105 may then be able to detect the change in the magnetic field of the object 203, which may indicate a first edge 210 of the object 203. As the metal detector 105 continues to pass over the object 203, the magnetic field of the object 203 may remain constant until the field 301 of the detector 105 reaches a second edge 215 of the object 203, in which instance the magnetic field of the object 203 changes again and is sensed by the detector 105. In such instances, the detector 105 may be able to determine the size of the object 203. In embodiments where the object 203 comprises first and second edges 210, 215 proximate each other, the detector 105 may only briefly induce a magnetic field in the object 203.
When a metal object 203 is detected which may interfere with the milling tools 101, the milling tools 101 may be raised such that the milling tools 101 pass over the metal object 203, as indicated by the vertical arrow 204, which may prevent damage to the metal object 203 and/or the milling tools 101. Other components such as a moldboard 205 may be raised to prevent damage as well. The components may be manually controlled by a machine operator or it may be automatically controlled by electronic equipment in a closed-loop system.
Referring now to the embodiment of
The electrically conductive coil 300 may be disposed within an electrically insulating material 400 in the trough 301, as in the embodiment of
As the coil 300 conducts an electrical signal, a magnetic field 401 is created around the coil 300 (though only part of the magnetic field 401 is shown). The MCEI trough 301 may be designed to direct the magnetic field 401 down into the paved surface. This may provide magnetic shielding for the metal detector 105, such that metal on the milling machine 100 which may be proximate the metal detector 105 may not interfere with the metal detector 105.
A plurality of electrically conductive coils 300 may be disposed within the MCEI trough 301, as in the embodiment of
The detector 105 may be attached at a distance far enough away from the body 103 of the machine 100 such that metal in the body 103 doesn't interfere with the metal detector 105. The machine may comprise an extension 700 on the front end 106 of the machine 100 to which the metal detector 105 may be attached, as in the embodiment of
The machine may comprise a plurality of metal detectors 802, 804. The metal detectors 105 may be arranged in a plurality of arrays 800, such that each array 800 is positioned at a different distance above the surface 200, as in the embodiment of
The metal detector 105 may be attached to a translatable arm 900, as in the embodiment of
Another method for determining the depth of metal objects may be triangulation. The machine may comprise a plurality of detectors 1000, 1002 positioned at different angles, as in the embodiment of
The present invention may be used in a milling machine comprising a plurality of rotary bits 1100 as milling tools 101, as in the embodiment of
The machine may comprise a plurality of detectors 105 arranged in an array 1200, as in the embodiment of
Referring now to
The controller 1400 may control the way the electronic equipment 1415 interacts with mechanical devices such as the milling tools 101 or other elements on the machine. Processors 1401 may be used to process the information and feedback from the detectors 105 or sensors 1402 such as motion sensors 1403 on the machine or torque sensors 1403 on the milling tools for use in a closed-loop system or for use by an operator. The equipment 1415 may comprise memory 1408 for storing the information for use as the machine traverses the paved surface. The information may also later be used for statistical or analytical purposes, or when repaving the surface. When a metal object is detected, indicators 1405 may alert an operator with both lights 1406 and speakers 1407. The electronic equipment 1415 may comprise wireless communication circuitry 1409 such that information gathered by the detectors 105 or sensors 1402 may be transmitted to a remote location. The equipment 1415 may comprise power supplies 1412 such as voltage or current sources 1413, 1414, which may either be constant or variable for powering the detectors 105 or sensors 1402. The equipment 1415 may also comprise filters 1410, switches 1411, or other electronic devices for performing such functions as determining the type of ferrous metal of the object.
Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.
