Seal with contact element for pick shield

Formation degradation, such as pavement milling, mining, drilling and/or excavating, may be performed using degradation assemblies. In normal use, these assemb lies and auxiliary equipment are subjected to high impact, heat, abrasion, and other environmental factors that wear their mechanical components. Many efforts have been made to improve the service life of these assemblies, including efforts to optimize the method of attachment to the driving mechanism.

One such method is disclosed in U.S. Pat. No. 5,261,499 to Grubb, which is herein incorporated by reference for all that it contains. Grubb discloses a two-piece rotatable cutting bit which comprises a shank and a nose. The shank has an axially forwardly projecting protrusion which carries a resilient spring clip. The protrusion and spring clip are received within a recess in the nose to rotatably attach the nose to the shank.

Another such method is disclosed in U.S. Patent Publication No. 2008/0309146 to Hall, et al., which is herein incorporated by reference for all that it discloses. It discloses, in one aspect, a degradation assembly comprising a shank with a forward end and a rearward end, the rearward end being adapted for attachment to a driving mechanism, with a shield rotatably attached to the forward end of the shank. The shield comprises an underside adapted for rotatable attachment to the shank and an impact tip disposed on an end opposing the underside. A seal is disposed intermediate the shield and the shank.

In one aspect of the present invention, a degradation assembly comprises a pressing seal element and a pressurized rigid element disposed intermediate a rotating component and a stationary component. The stationary component may be attached to a driving mechanism through a block. The rotating component may comprise an impact tip bonded to an end opposing the stationary component. The seal element may energize the rigid element against one of the components to form a slidable seal capable of holding lubricant within the assembly and keeping debris out while still rotating.

The rotating element may comprise a shield with a recess opposite the impact element. The recess of the shield may rotatably connect to the first end of a shank. A second end may be retained in a holder attached to a driving mechanism. In another embodiment, the shield and the shank may comprise a single component and rotate with respect to the holder. A pressing seal element may be disposed intermediate the rotating component and the stationary component, and a pressurized rigid element may be disposed adjacent to the seal element.

The rigid element may comprise a concave and/or textured surface facing the seal element and a flat, convex, polished, and/or wear resistant surface opposing the seal element.

The seal element may comprise an O-ring, a rubber washer, or a compression spring. The seal element may comprise a textured outer surface. The assembly may comprise a wiper or a ring disposed axially around the assembly, adjacent to both the shield and the shank. The assembly may comprise a lubricant chamber. The assembly may comprise a spring clip. The shank may comprise a ledge. The assembly may comprise a pick.

FIG. 1 is a cross-sectional diagram of an embodiment of a pavement milling machine.

FIG. 2 is a cross-sectional diagram of an embodiment of a degradation assembly.

FIG. 3 is a cross-sectional diagram of another embodiment of a degradation assembly.

FIG. 4 is a cross-sectional diagram of another embodiment of a degradation assembly.

FIG. 5 is a cross-sectional diagram of another embodiment of a degradation assembly.

FIG. 6 is a cross-sectional diagram of an embodiment of a degradation assembly retained in a holder and further retained in a block.

FIG. 7 a is a perspective diagram of an embodiment of a rigid element.

FIG. 7 b is a perspective diagram of an embodiment of a protective ring.

FIG. 7 c is a cross-sectional diagram of an embodiment of a protective ring with a wiper.

FIG. 7 d is a perspective diagram of an embodiment of an O-ring.

FIG. 7 e is a perspective diagram of an embodiment of a rubber washer.

FIG. 1 is a cross-sectional diagram of a pavement milling machine 103 that shows a plurality of pick degradation assemblies 101 attached to a driving mechanism 102 , such as a rotatable drum, attached to the underside of the pavement milling machine 103 . The pavement milling machine 103 may be an asphalt planer used to degrade man-made formations 104 such as pavement, asphalt, concrete, tarmac, blacktop or other manmade formations known in the art prior to placement of a new layer of the formation 104 . The formation 104 may also comprise naturally occurring material such as stone, dirt, minerals, rubble, debris or the like. The pick degradation assemblies 101 may be attached to the rotatable drum, bringing the pick degradation assemblies 101 into engagement with the formation 104 . A holder 105 , such as a block or other type holder, is attached to the driving mechanism 102 by means of a weld, bolt(s) or other sturdy fastening means known in the art. The pick degradation assembly 101 may be inserted into the holder 105 . The holder 105 may hold the pick degradation assembly 101 at an angle offset from the direction of rotation, such that the pick degradation assembly engages the formation 104 at a preferential angle. While an embodiment of a pavement milling machine 103 was used in the above example, it should be understood that pick degradation assemblies 101 disclosed herein have a variety of uses and implementations that may not be specifically discussed within this disclosure.

It is believed that while in use, a nonrotatable pick degradation assembly 101 may receive uneven wear on a single side because the same side is continuously engaging a formation 104 . This uneven wear may shorten the life of the pick degradation assembly 101 . It is further believed that the life of the assembly 101 may be lengthened by rotating the assembly such that different sides of the assembly 101 are engaging the formation 104 throughout the life of the pick degradation assembly 101 .

Referring now to FIG. 2 , a cross-sectional view of an embodiment of a pick degradation assembly 101 A is depicted. The pick degradation assembly 101 A may comprise a shield 202 A and a shank 201 A. The shield 202 A may comprise a recess 215 A. The recess 215 A may be a blind recess 215 A that travels into the shield 202 A without passing out the other side. The recess 215 A may be rotatably connected to the shank 201 A. A spring clip 208 A within the recess 215 A may secure the shield 202 A over the shank 201 A while still allowing the shield 202 A to rotate relative to the shank 201 A. The spring clip 208 A may be compressed to allow the shield 202 A to fit over the shank 201 A and then spring back substantially to its original form once within a depression or other ledge within the shank 201 A. The shield 202 A may have an axial diameter 250 sufficient to cover the shank 201 A and generally protect it from impact with a formation. The shield 202 A may form a cap over the shank 201 A. The side of the shield 202 A opposite the recess 215 A may comprise a frustum or a substantially conical geometry. The substantially conical geometry may comprise an impact tip 203 A bonded to the shield 202 A opposing the recess 215 A.

The impact tip 203 A may comprise a super hard material 211 A bonded to a carbide substrate 210 A. The super hard material 211 A may comprise diamond, polycrystalline diamond with a binder concentration of 1 to 40 percent weight, cubic boron nitride, refractory metal bonded diamond, silicon bonded diamond, layered diamond, infiltrated diamond, thermally stable diamond, natural diamond, vapor deposited diamond, physically deposited diamond, diamond impregnated matrix, diamond impregnated carbide, monolithic diamond, polished diamond, coarse diamond, fine diamond, non-metal catalyzed diamond, cemented metal carbide, chromium, titanium, aluminum, tungsten, or combinations thereof.

The shank 201 A may remain stationary with respect to a holder (not shown). The shank 201 A may comprise a ledge 214 A that may flare out to meet the shield 202 A. The ledge 214 A may have a ledge diameter 252 larger than a shank diameter 254 of the majority of the shank 201 A. The shank 201 A may include a lubricant chamber 204 A. The pick degradation assembly may also comprise a seal 206 A, 209 A and a protective ring 205 A. A rigid element 207 A may be disposed adjacent to the seal 206 A, 209 A. The rigid element 207 A and seal 206 A, 209 A may be disposed adjacent to the ledge 214 A.

The shield 202 A may be able to freely rotate around the shank 201 A. The lubricant chamber 204 A may dispense lubricant intermediate, or between, the shank 201 A and the shield 202 A. The lubricant may aid in the rotation of the shield 202 A with respect to the shank 201 A. It is believed that by allowing the shield 202 A to freely rotate around the shank 201 A, that the wear on the pick degradation assembly 101 A during operation will on average be spread around the entire assembly as opposed to just a single side. Furthermore, it is believed that by spreading the wear around the entire assembly 101 , the assembly 101 may last longer.

The seal 206 A, 209 A may be disposed intermediate, or between, the shank 201 A and the shield 202 A. The seal may comprise an O-ring 209 A and a rubber washer 206 A. The seal 206 A, 209 A may serve the purpose of sealing lubricant within the pick degradation assembly 101 A and keeping dirt and debris from penetrating the space intermediate, or between the shield 202 A and the shank 201 A. A protective ring 205 A may be disposed axially around the assembly 101 A, adjacent to both the shield 202 A and the shank 201 A. The protective ring 205 A may prevent particles from entering the vicinity of the rigid element 207 A and the seal 206 A, 209 A. The protective ring 205 A may comprise a wiper 255 (see FIG. 7 c ), a metal ring, a plastic ring, or another ring of sufficient dimensions to be disposed around the pick degradation assembly 101 A while limiting access to the space intermediate, or between, the shank 201 A and the shield 202 A. It is believed that the seal 209 A, 206 A may prematurely wear and fail if it is physically exposed to the rotating surface of the pick degradation assembly 101 A. A rigid element 207 A disposed adjacent to the seal 209 A, 206 A may extend the life of the seal 209 A, 206 A.

The rigid element 207 A may comprise a ring with a concave inner surface 213 A. The rigid element 207 A may comprise a metal. The rigid element 207 A may be disposed between the shank 201 A and the shield 202 A. The concave inner surface 213 A of the rigid element 207 A may be disposed adjacent to the O-ring 209 A such that the O-ring 209 A lies within a contour of the rigid element 207 A. The concave inner surface 213 A may comprise a texture. The textured surface may allow the rigid element 207 A to more easily engage the O-ring 209 A. The O-ring 209 A may also comprise a textured surface to further aid in a frictional engagement with the rigid element 207 A. The rigid element 207 A may also have a surface that engages the rubber washer 206 A. It is believed that the friction created by the interaction between the rigid element 207 A, the O-ring 209 A and the rubber washer 206 A may prevent the rigid element 207 A from rotating with respect to the shank 201 A.

The rigid element 207 A may also comprise a flat surface 212 A. The flat surface 212 A may be polished such that it is smooth. The flat surface 212 A may be adjacent to the shield 202 A. The polished flat surface 212 A of the rigid element 207 A may provide a surface for the shield 202 A to rotate upon with respect to the shank 201 A. The rigid element 207 A may place the O-ring 209 A under compression. The elastic nature of the O-ring 209 A may in turn place an opposing force on the rigid element 207 A forcing it into contact with the shield 202 A. As the pick degradation assembly 101 A is used and the shield 202 A rotates with respect to the shank 201 A, the friction exerted by the shield 202 A onto the polished flat surface 212 A of the rigid element 207 A may cause it to wear and grow thinner. It is believed that the force exerted by the O-ring 209 A onto the rigid element 207 A will force the rigid element 207 A to remain in contact with the shield 202 A even after it has become worn.

In some embodiments the rigid element 207 A may comprise a wear resistant surface 212 A. The wear resistant surface 212 A may comprise a material such as diamond, cubic boron nitride, lonsdaleite, tungsten carbide, or a combination thereof. The wear resistant surface 212 A may aid in extending the useable working life of the pick degradation assembly 101 A.

Now referring to the embodiment of a pick degradation assembly 101 B depicted in FIG. 3 , a rigid element 207 B has been flipped 180 degrees with respect to the rigid element 207 A in FIG. 2 . A rubber washer 206 B has been disposed in a shield 202 B instead of in the shank 201 A as in FIG. 2 . In this embodiment the rigid element 207 B may be frictionally engaged with the shield 202 B, such that during rotation, the rigid element 207 B may remain stationary with respect to the shield 202 B. In this embodiment, a flat surface 212 B may be adjacent to a shank 201 B.

Referring now to FIG. 4 , a rigid element 207 C may comprise a convex surface 401 . The convex surface 401 may extend into the shield 202 C. During degradation operations the degradation pick assembly 101 C may experience lateral jarring and vibrations. It is believed that the convex surface 401 may provide the shield 202 C with additional lateral stability during rotation and degradation operations. This additional support may extend the life of the pick degradation assembly 101 C by lowering the amount of wear that the pick degradation assembly 101 C receives.

Referring now to FIG. 5 , a pick degradation assembly 101 D may comprise a spring 501 . The spring 501 may be disposed intermediate, or between, a rigid element 207 D and a shank 201 D. The spring 501 may exert a force onto the rigid element 207 D pushing the rigid element 207 D into contact with a shield 202 D. This may aid in maintaining contact between the rigid element 207 D and the shield 202 D as the rigid element 207 D wears. A rubber washer 206 D may function as a seal.

Referring now to FIG. 6 , a pick degradation assembly 101 E may be retained in a holder 605 and further retained in a block 620 . The pick degradation assembly 101 E may also comprise a shield 602 and a shank 601 . In this embodiment, the shield 602 may be rigidly connected to the shank 601 and rotate within the holder 605 together with the shank 601 . An impact tip 603 may be bonded to the distal end of the shield 602 , the impact tip comprising a superhard material 611 bonded to a carbide substrate 610 . A rigid element 607 may be disposed intermediate, or between, the shield 602 and the holder 605 . The rigid element 607 may be pressurized by a pressing seal element 606 , 609 . In this embodiment the seal element 606 , 609 comprise a rubber washer 606 and an O-ring 609 . The seal element 606 , 609 may press the rigid element into the holder 605 as shown or alternately into the shield 602 . This embodiment may allow the shield 602 and shank 601 to rotate relative to the holder 605 while maintaining lubricant within the assembly 101 E.

FIGS. 7 a , 7 b, 7 c, 7 d and 7 e depict embodiments of various components of a pick degradation assembly. FIG. 7 a depicts an embodiment of a rigid element 207 F. The rigid element 207 F may comprise a rigid and wear resistant material such a metal. The rigid element 207 F may comprise a concave inner surface 213 F. The concavity of the surface 213 F may change based upon the O-ring size that it is designed to receive.

FIG. 7 b depicts an embodiment of a protective ring 205 F. The protective ring 205 F may comprise a rigid material such as metal or plastic. The girth of the protective ring 205 F may substantially cover any gap that may exist between a shield and a shank. It is believed that the protective ring 205 F may aid in preventing debris from penetrating between the shield and the shank.

FIG. 7 c depicts a cross-sectional view of another embodiment of a protective ring 205 G comprising a wiper 255 G. The wiper 255 G may comprise an elastic material. It is believed that the wiper 255 G may further aid in preventing debris from penetrating between a shield and a shank.

FIG. 7 d depicts an embodiment of an O-ring 209 G. The O-ring 209 G may comprise an elastic material.

FIG. 7 e depicts an embodiment of a rubber washer 206 G. The rubber washer 206 G may function as a seal and as a friction surface.

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.