Patent Publication Number: US-2007116519-A1

Title: Systems and Methods for Milling Paving Material with Increased Stability, Support, and Power

Description:
RELATED APPLICATIONS  
      This application claims priority to U.S. Provisional Application Ser. No. 60/348,063, filed Jan. 9, 2002, and entitled, “Systems and Methods for Milling Paving Material with Increased Stability, Support, and Power,” which is incorporated by reference herein. 
    
    
     BACKGROUND  
      1. Field of the Invention  
      The present invention relates to systems and methods for milling paving material. More particularly, the present invention relates to systems and methods that provide increased stability, support and power while grinding paving material.  
      2. Background of the Invention and Related Art  
      Asphalt milling is a technique currently employed to remove asphalt pavement for reconstruction or resurfacing, and for accessing buried utility lines. The technique involves the removal of asphalt pavement through the use of a cold planer, which can remove up to approximately two inches of pavement surface during a particular pass.  
      A cold planer typically includes a barrel-like attachment, referred to as a mandrel, and a variety of bits (e.g., 40) that are affixed to the exterior surface of the mandrel. Coupled to the cold planer is a vehicle (e.g., a bobcat or skid-steer) that is used to propel the cold planer. The mandrel rotates and is pushed into the pavement by the hydraulic system of the vehicle, causing the bits to grind up the asphalt pavement. The vehicle pushes the cold planer as the mandrel rotates to grind a trench in the asphalt pavement that is typically up to 24 inches wide.  
      While this technique enables the creation of a trench that is up to 2 inches deep, various problems exist. For example, traditional cold planers stall out upon attempting to grind 2-3 inches of asphalt pavement. Thus, when desiring to mill a depth of 6 inches of pavement, at least three passes of the cold planer must be conducted. Furthermore, the milled asphalt composite left behind in the wake of the cold planer must be removed between each pass. As a result, this process has proven to be time consuming.  
      The process is further delayed by the requirement of having to push the cold planer at an extremely slow rate. Much of the power from the skid-steer is used to rotate the mandrel. As such, limited power is available to push the cold planer forward. Typically, the cold planer creates a trench by grinding the pavement at a rate of up to ½ mph.  
      The process is further hampered by instability. The vehicle used to propel the cold planer typically loses traction and has a tendency to shake. A loss in pressure between the actions of providing pressure on the cold planer and lowering the mandrel also yields to instability. Moreover, a procedure of edge milling typically requires the removal of supporting structures of the cold planer, triggering further instability.  
      Thus, while the traditional technique of asphalt milling enables the creation of a milled trench that is up to 2 inches deep, the technique has proven to be instable and time consuming. Accordingly, it would be an improvement in the art to augment or even replace existing techniques to enable a trench to be milled in asphalt pavement at a quicker rate and/or to provide increased stability to the milling process.  
     SUMMARY AND OBJECTS OF THE INVENTION  
      The present invention relates to systems and methods for milling paving material. More particularly, the present invention relates to systems and methods that provide increased stability, support and power while grinding paving material.  
      Implementation of the present invention takes place in association with a self-powered milling system for use in milling or grinding asphalt and is configured for coupling to a vehicle (e.g., a bobcat, steer-skid, or other vehicle) that selectively pushes or pulls the milling system in a desired direction. The milling system includes a cylindrical mandrel, having a variety of bits attached thereon, which spins on an axis to break up and mill the asphalt. The mandrel is powered by a milling system motor that speeds up production and enables milling of very thick asphalt (e.g., 8 inch thick asphalt) in a single pass. A breaker bar of the milling system is continuously located at or near ground level during the milling process to hold the asphalt down as it tries to lift up during the process. The breaker bar further assists in breaking up the milled asphalt aggregate.  
      In one implementation, the milling system includes a carriage that follows the contour of the ground. The carriage provides stability during the milling process, allowing only the mandrel or cutting head to move during the process. The carriage may be selectively adjusted to provide cuts at various angles. Furthermore, the carriage is designed to include a flush side to enable use of the milling system in performing precise edge milling of the asphalt.  
      While the methods and processes of the present invention have proven to be particularly useful in providing increased stability, support and power in the area of milling asphalt, those skilled in the art shall appreciate that the methods and processes can be used to mill a variety of different surfaces.  
      These and other features and advantages of the present invention will be set forth or will become more fully apparent in the description that follows and in the appended claims. The features and advantages may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Furthermore, the features and advantages of the invention may be learned by the practice of the invention or will be obvious from the description, as set forth hereinafter.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In order that the manner in which the above-recited and other advantages and features of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:  
       FIG. 1  illustrates a perspective view of a representative embodiment of the present invention;  
       FIG. 2  illustrates a front view of the embodiment of  FIG. 1 ;  
       FIG. 3  illustrates a perspective view of a representative cutting head that may be used in association with the embodiment of  FIG. 1 ;  
       FIG. 4  illustrates a side view of the embodiment of  FIG. 1 ; and  
       FIG. 5  illustrates a top view of the embodiment of  FIG. 1 .  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      It will be readily understood that the components of the present invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, and represented in  FIGS. 1 through 5 , is not intended to limit the scope of the invention, as claimed, but is merely representative of the presently preferred embodiments of the invention.  
      The presently preferred embodiments of the invention will be best understood by reference to the drawings wherein like parts are designated by like numerals throughout.  
      The present invention relates to systems and methods for milling paving material. More particularly, the present invention relates to systems and methods that provide increased stability, support and power while grinding paving material.  
      In the disclosure and in the claims the term “paving material” shall refer to any material that may be used to pave a road, path, sidewalk, parking lot, driveway, thoroughfare, or any other similar surface. Examples of paving materials include asphalt, tarmac, pavement, cement, clay, stone and dirt.  
      Embodiments of the present invention take place in association with a self-powered milling system for use in milling or grinding paving material, and which may be configured to be coupled to a vehicle (e.g., a bobcat, steer-skid, back hoe, excavator or other vehicle) that selectively pushes or pulls the self-powered milling system in a desired direction. The milling system includes a cutting head, such as a cylindrical mandrel that includes a variety of bits attached thereon. The mandrel spins on an axis to break up and mill the paving material, and is powered by a milling system motor that speeds up production and enables the milling of very thick paving material (e.g., 8 inch thick asphalt) in a single pass.  
      Embodiments of the present invention further embrace a milling system having a carriage that follows the contour of the ground. The carriage provides stability during the milling process, allowing only the cutting head to move during the process, and may be selectively adjusted to provide cuts at various angles. In a further embodiment, the carriage includes a flush side to enable performance of precise edge milling.  
      In one embodiment, a breaker bar is coupled to the carriage. The breaker bar is continuously located at or near ground level to hold the asphalt down as it tries to lift up during the milling process. The breaker bar is further employed to assist in the breaking up the milled asphalt aggregate.  
      As provided above, embodiments of the present invention take place in association with a self-powered milling system that may be used to mill or grind paving material, and that may be configured to be coupled to a vehicle (e.g., a bobcat, steer-skid, back hoe, excavator or other vehicle), which selectively pushes or pulls the self-powered milling system in a desired direction. With reference to  FIG. 1 , a representative embodiment of a self-powered milling system is illustrated as milling system  10 , which includes cutting head  12  having bits  14  attached thereon, motor  16 , carriage  18 , wheels  20 , and vehicle coupler  22 .  
      In  FIG. 1 , milling system  10  is configured to be coupled to a vehicle using vehicle coupler  22 . In the illustrated embodiment, vehicle coupler  22  is adjustable to allow for a coupling of milling system  10  to any type of vehicle. Once coupled to milling system  10 , the vehicle (not shown) may be operated by a user to selectively push or pull milling system  10  in a particular direction.  
      Milling system  10  comprises a motor  16 , which is separate from the motor of the vehicle. As such, milling system  10  is self-powered to enable the grinding or milling of paving material. More specifically, motor  16  is dedicated to the actuating of cutting head  12  in order to grind or mill paving material under milling system  10 .  
      The use of cutting head  12  is more fully illustrated in  FIGS. 2 and 3 . In  FIG. 2 , a front view of milling system  10  is provided. Cutting head  12  is actuated by motor  16  and spins on an axis. As cutting head  12  is spinning, milling system  10  is pushed by a vehicle coupled thereto and mills paving material that passes underneath cutting head  12 .  
      With reference now to  FIG. 3 , a perspective view of cutting head  12  is illustrated. In  FIG. 3 , cutting head  12  is a barrel-like attachment, known as a mandrel. The mandrel spins and is pushed into the paving material. Bits  14  affixed to the exterior of the mandrel engage and grind up the asphalt. Once ground, the asphalt may be easily removed and replaced.  
      In one embodiment, approximately forty bits are located on the exterior surface of cutting head  12 . The bits  14  are scattered and patterned along the mandrel in a way that optimally enables pulverization and are exposed to the asphalt when the mandrel is in operation. In addition to the bits on the exterior of the mandrel, six bits are located at each end of the mandrel. The end bits prevent the mandrel from wedging into the paving material and from becoming stuck, and are known as “inside end bits.” 
      Each bit  14  has a hardened or carbide tipped end, a stem, and a flat end at the bottom of the stem. The bits  14  are attached to a mandrel by their insertion into channels or blocks of the mandrel. In one embodiment, the stem of a bit  14  has a spring collet surrounding it. When the bit is forced into a channel of a bit block and pressed down through the shaft, the spring collet squeezes against the stem to tightly fit the stem within the channel. An annular space on the bit that engages a lipped section of the top end of the bit shaft and locks the bit into the shaft is located between the bit stem and the tipped end of the bit. This annular space prevents the tip from leaving the shaft.  
      A bit  14  may be removed, such as when it has become tipped out, by pounding on the exposed flat end of a bit  14  seated within the shaft, and drive the bit  14  from the shaft. The bit is removable because despite its secure fit within the shaft, when the flat end is impacted, the spring collet is forced inward to contract and pass by the lip of the shaft and is released from the annular space within the bit block.  
      Unfortunately, due to wear and tear, bits require replacement. For example, when an operator of milling system  10  hits a manhole, bits may become tipped out and need replacement. The need for replacing bits  14  arises frequently, therefore time efficient and cost effective techniques for replacing bits is greatly desired.  
      In the illustrated embodiment, and with reference back to  FIG. 1 , a bit access is provided to facilitate bit removal from a top-level or a top portion of milling apparatus  10 . The bit access is illustrated as removable cover  30 , which is hinged to a casing that covers cutting head  12 . In another embodiment, removable cover  30  is mechanically removable. Cover  30  provides access to bits  14  and facilitates access by eliminating the traditional requirement of having to access bits  14  from underneath a cold planer.  
      In the illustrated embodiment, removable cover  30  removes a top portion from a casing that covers cutting head  12  as well as a portion of either side of the casing. As such, in one embodiment, the top 60° to 90° of the cutter head  12  is exposed when removing removable cover  30 . Since a portion on each of the sides of the casing is removable, access to the inside end bits is facilitated.  
      The use of motor  16  to drive cutting head  12  eliminates the need of traditional practices to steal power from the vehicle motor (not shown). The use of motor  16  exponentially speeds up production (it is approximately 4-6 times faster than traditional methods) since it enables the vehicle motor to be dedicated to moving system  10  and further enables up to approximately 8 inches of paving material to be milled in a single pass, as opposed to 2 inches by traditional methods. As such, the time required for an operator to perform the milling of paving material is greatly reduced since up to 8 inches can be milled with each pass.  
      Thus, for example, a traditional cold planer that claims it can mill up to 6 inches deep actually requires three separate passes, where each pass mills 2 inches of the paving material, in order to mill the total 6 inch deep paving material. Furthermore, a traditional milling head requires approximately 72 hp to run effectively. An average skid-steer motor doesn&#39;t generally produce more than 72 hp, which must be used to spin the milling head and to push the cold planer. Therefore, since so much of the power is required to spin the milling head, the amount of power available to push the cold planer is limited and results in an extremely slow process. Typically, the traditional cold planer is only able to mill up to about 2 inches deep and is only pushed at ½ mph.  
      In contrast, in accordance with the present invention, power (e.g.,  72  hp or another amount of power) from the vehicle motor is provided to selectively move/push the milling system  10 , and an additional amount of power (e.g., another 72 hp or another amount) is provided to spin the cutting head  12 . The increased power yields increased efficiency in performing a milling job.  
      Embodiments of the present invention further increase the ability to mill paving material by providing a belt-driven system to power a cutting head. Traditionally, vehicles used to power a traditional cold planer are powered through the utilization of a hydraulic system, which yields a high efficiency loss. For example, a hydraulic system is typically about 60% efficient. Thus in the example above, where in a traditional procedure 72 hp is available to both move a traditional cold planer and to spin a cutting head, the actual power available due to the hydraulic system is 43.2 hp (72 hp multiplied by 60% efficiency is 43.2 hp). The other 28.8 hp is lost in heat.  
      In contrast, embodiments of the present invention embrace the use of a belt-driven system  34 , which provides 90% to 95% efficiency. Thus, where motor  16  provides 72 hp, milling system  10  is actually placing 64.8 (72 hp multiplied by 90% efficiency is 64.8 hp) on spinning cutting head  12 . The belt-driven system  34  is additionally illustrated in  FIGS. 4 and 5 , which are respectively a top view and a side view of milling system  10 , and includes a belt and a transmission  64  ( FIG. 5 ). The belt couples shaft  42  ( FIG. 3 ) of cutting head  12  with motor  16  to cause motor  16  to rotate shaft  42  and cause cutting head  12  to spin.  
      In one embodiment, system  10  further includes a belt tensioning system  60  ( FIG. 5 ), such as an automatic or manual tensioner, that keeps the belt of the belt-driven system taut. In a further embodiment, the belt-tensioning system  60  includes a pneumatic air cylinder  62  ( FIG. 5 ). As such, the belt may be set and aligned with low to no tension and locked into place. The belt-tensioning system  60  may then be engaged to apply tension to the belt in order to keep the belt taut. In one embodiment, the tension automatically adjusts to pressure. Therefore, when the system  10  hits, for example, an object while in use, the belts are automatically kept taut.  
      With reference back to  FIG. 1 , milling system  10  provides a carriage  18 , which sits near the ground and provides support. In one embodiment, carriage  18  sits approximately one-half inch above the ground. In the illustrated embodiment, wheels  20  are coupled to carriage  18 . Carriage  18  provides pressure on cutting head  12 .  
      Carriage  18  includes a flush side  26  that enables edge milling of paving material. For example, when milling system  10  is used to mill paving material that is located up against a vertical surface, milling system  10  is pushed along the vertical surface with the flush side  26  near the vertical surface. As such, the paving material may be milled within three to four inches of a vertical surface without touching the sides of milling system  10 . The remaining portion of paving material may then be knocked off with a shovel. In contrast, traditional techniques required disassembly of a cold planer, which has caused instability in using the cold planer. The use of carriage  18  further allows for carriage  18  to potentially bump the vertical surface rather than cutting head  12 , which would damage the vertical surface.  
      Carriage  18  is configured to be selectively adjusted to enable milling system  10  to be used in such a way as to cut on a particular angle or taper. Embodiments of the present invention embrace the ability to manually or hydraulically adjust the height of wheels  20 . Milling system  10  maintains traction and support by allowing carriage  18  to follow the ground while cutting head  12  follows the set angle. In contrast, traction is lost in traditional techniques.  
      Milling system  10  may be manually or hydraulically tipped through the use of a cylinder, such as cylinder  28 . For example, cylinder  28  is locked for safety reasons while moving milling system  10 . Once milling system  10  is in use, cylinder  28 , which allows cutting head  12  to raise and lower, may be manually or hydraulically actuated to allow cutting head  12  to move back and forth. In other words, cutting head  12  is allowed to float, which allows equal traction for the vehicle used. While milling, cutting head  12  is allowed to adjust to whatever angle it needs to in order to adjust and follow the contour of the ground. As such, multi-vector positioning of cutting head  12  is made possible.  
      Embodiments of the present invention embrace an improved method for entering the ground in order to mill paving material. In one embodiment, the vehicle is locked up in a home position and the arms of the vehicle are locked down with the tilt locked back. In this manner, nothing shakes or vibrates. Pressure is provided onto cutting head  12  by cylinder  28 , and motor  16  engages cutting head  12  to allow for the milling to occur. As such, embodiments of the present invention may be dropped into any asphalt or paving material and pulverize the paving material into a fine gravel, similar to a road base.  
      Thus, a first cylinder, illustrated as cylinder  28 , holds cutting head  12  down into the ground, pulling between carriage  18  and cutting head  12 . A second cylinder controls the tilt that is enabled by milling system  10  and has the extra option of allowing cutting head  12  to float while in use to enable a more effective milling. In one embodiment, as illustrated in  FIG. 4 , system  10  pivots about pivot point  52 . A third cylinder is utilized to shift the vehicle hook-up.  
      With reference back to  FIG. 1 , a bearing  32  faces outward and is protected from any debris, such as rocks, that may be spinning around. In one embodiment, a mound sets bearing  32  inside cutting head  12 , but facing out to provide access to grease bearing  32 . Alternatively, a user may pop bearing  32  out and remove it without disassembling any other portion of milling system  10 . Alternatively, the cutting head  12  may be dropped out from system  10  and replaced with another cutting head. Thus, bearing  32  is placed inside the cutting head  12 , facing out where it is still protected.  
      Also inside cutting head  12  is a well mount or a gear reduction planetary that is mounted to one side of the drum and to the frame. On the other side of the drum an outboard shaft is mounted with an outboard bearing support to help the cutting head ride. This increases the life span of the gearbox and virtually provides an unlimited life span of the gear reduction planetary.  
      In a further embodiment, a remote control system is utilized to provide control of the various cylinders in order to guide or steer milling system  10 . In one embodiment, the remote control system utilizes a radio control system, such as an RF frequency, to provide the control. The system has an E-stop with a continuous transmission. If an operator gets far enough away from milling system  10 , the system shuts down automatically.  
      In a further embodiment, milling system  10  includes an extended drive input. A shaft with a flex coupling that includes a couple of bearings that have two pilot tubes that bolt up to cutting head  12  and support the belt enable the engine to be flush on side  26  rather than having to overhang approximately 12 inches.  
      Embodiments in the present invention further embrace a large frame that holds still, just allowing the cutter head to move up and down. In other words, the vehicle frame is extended 10 feet or longer by the use of the carriage of the milling system. Furthermore, a breaker bar illustrated as breaker bar  24 , is continuously located at ground level to hold the pavement down as it tries to lift up and is used to help break up the aggregate that has been milled.  
      Thus, as discussed herein, the embodiments of the present invention embrace systems and methods that provide increased stability, support and power in milling paving material. The present invention may be embodied in other specific forms without departing from its spirit of essential characteristics. The described embodiments are to be considered in all respects only al illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.