Wear Element for a Scraping Operation

The present invention pertains to wear inserts. More specifically, the present inserts are particularly adapted for use in earth and road working machines, such as graders, scrapers, snow plows and the like.

Earth and road working machines, such as graders, are used primarily to maintain or create a desired ground surface. The operation is typically accomplished by a machine having a mold board or like construction. A mold board is a long scoop-like member having a slight concave surface facing in the direction of travel. The mold board is pushed across the ground or road by the machine to perform a scraping-grading type action. As can be appreciated, such an operation subjects the mold board to harsh treatment, and left unchecked would quickly ruin the mold board. To avoid premature wearing of the mold board, a wear element is secured along the mold board's lower edge.

One common wear element used to protect mold boards is an elongate blade member. The blade members are generally fabricated in three and four foot long increments and bolted end-to-end across the entire lower edge of the mold board. With this construction, the blade forms a continuous working edge which engages the ground surface and protects the mold board. An example of such a blade is disclosed in U.S. Pat. No. 4,770,253 to Hallissy et al. After a certain length of time, the worn blades are replaced instead of the much more costly mold board.

Another common wear element used to protect mold boards involves a modified form of the blade and a plurality of picks. More specifically, the modified blade member is secured to the lower edge of the mold board. Like the wear blades discussed above, these blades are fabricated in three and four foot long increments and positioned end-to-end across the mold board. However, instead of a lower working edge, the blade defines means for securing the picks. The picks are generally bolted to the face of the blade or releasably retained (e.g., by a clip) within a socket defined in the blade. In any event, a plurality of the picks are secured in place along the blade to collectively form a discontinuous working edge for engaging the ground surface. Each pick defines a generally linear edge comprising a segment of the working edge. One example of such a wear element is disclosed in U.S. Pat. No. 4,753,299 to Meyers. In this construction, only the picks generally require replacement. Alternatively, the discontinuous edge can also be formed by a specially configured blade member, such as shown in U.S. Pat. No. 3,192,653 to Socin.

In order to increase the useful life of the wear element, its working edge is often provided with a hardened insert. The insert forms the leading face and at times the bottom face, to maximize the protection afforded the wear element. The inserts are generally brazed to the wear element along one or two mounting faces. The inserts, however, are at times broken off from the wear element. Once the insert is lost, the wear element is quickly worn away and ruined. This results not only in higher maintenance and repair costs, but also increased down time for the machine.

The present invention is directed to wear inserts which protect and lengthen the useful life of an element subjected to abrasive conditions. The inserts of the present invention have particular usefulness in earth and road working machines, such as graders, scrapers and snow plows. Nonetheless, the present inserts could be used in other abrasive environments.

The present wear insert is formed with a general U-shaped configuration which defines a pair of opposed legs and a central gap therebetween. The gap enables the insert to wrap around a mounting flange of the protected element to greatly reduce the risk of breaking the insert from the element. Preferably, the insert includes six discrete mounting faces which are each fixed to the working element to preclude its unintended removal. Moreover, selected corners of the insert are chamfered to facilitate the flow of a brazing flux across all the mounting faces during fabrication.

FIG. 1 is a perspective view of a grader blade assembly including the present invention.

FIG. 2 is a cross sectional view taken along line 2--2 in FIG. 1.

FIG. 3 is a perspective view of an alternative grader blade assembly including the present invention.

FIG. 4 is a cross sectional view taken along line 4--4 in FIG. 3.

FIG. 5 is an enlarged side view of the insert and pick construction illustrating the fabrication of the present invention.

FIG. 6 is a perspective view of a wear insert in accordance with the present invention.

FIG. 7 is a top plan view of the wear insert.

Wear insert 10 (FIGS. 6 and 7), in accordance with the present invention, is adapted to form a protective barrier for the member to which it is attached. In the preferred construction, wear inserts 10 are fixed to the lower edge of mold board assemblies 12 (FIGS. 1 and 3), such as used in graders, scrapers, snow plows and the like. Assemblies 12 generally comprise a mold board 14 and a plurality of wear elements 16. Wear element 16 may be an elongated blade member 16a, or a blade and pick construction 16b. The elongate blade member 16a and the blade and pick construction 16b operate in essentially the same way as in the prior art devices. Wear elements 16 are secured along the lower edge 18 of the mold board, so that they engage and work the ground or road surface and thereby protect the mold board. Since the wear elements 16 are subjected to abrasive conditions, they are equipped with wear inserts 10 to maximize their useful life.

Wear insert 10 has a generally U-shaped configuration which is designed to wrap around a mounting flange 26 of the protected member 16 to reliably hold the insert in place (FIGS. 1-4). More specifically, insert 10 is comprised of a front leg 28, a rear leg 30 and a lower bight segment 32 (FIGS. 2 and 4-7). The spaced apart legs 28, 30 include inner walls 34, 36, respectively, to cooperatively define a central gap 38 therebetween. The inner boundary of gap 38 is defined by end wall 40. These three walls define three independent mounting surfaces which, as discussed below, are fixed to corresponding surfaces defined by the wear element 16. Additional mounting surfaces are defined by top wall 42 of front leg 28 and the top and rear walls 44, 46 of rear leg 30.

Insert 10 further defines a generally upright leading surface 48 which faces in the direction of movement when the insert is mounted to member 16. Leading surface 48 is adapted to engage and accept the impact and other wearing forces associated with the operation. The bottom surface 50 of the insert is formed by a pair of angled segments 52, 54. Tip segment 52 extends rearwardly from leading surface 48 at about a right angle. The intersection of the leading and tip surfaces form the front leading edge 56 of the insert. The tip surface 52 is drawn along the ground or road and generally accepts wearing forces during the operation. The mold board may be oriented so that the leading surface is upright or inclined slightly in either direction. The wearing forces will vary depending on the particular operation. Sloped segment 54 is angled to slope upwardly and rearwardly from tip segment 52 at an angle of about 25.degree. and preferably at 24.degree. 45'. Of course, it could be oriented at other angles. Sloped surface 54 is angled relative to tip segment 52 so that it lies above the ground or road surface when the mold board is rearwardly inclined.

The lower working portion of the protected member 16 is specially configured to accommodate the unique construction of the present invention (FIGS. 2, 4 and 5). Specifically, member 16 defines a pair of downwardly extending flanges 26, 60. Flanges 26, 60 extend transversely across member 16 in a spaced apart relationship to define a central groove 62 therebetween. In addition, front flange 26 is offset from the front face 64 of member 16 to define a forward groove 66. Grooves 62, 66 are shaped to matingly receive therein legs 28, 30 of wear insert 10. Preferably, legs 28, 30 are fit within their respective grooves 62, 66 to accommodate the flow of a brazing solder therebetween. The interlocked relationship between the legs 28, 30 of insert 10 and flanges 26, 60 of member 16 form an enhanced mounting arrangement for the insert that significantly reduces the risk of breakage.

Front flange 26 is defined by a pair of side faces 68, 70 and an end face 72. Likewise, rear flange 60 is defined by a pair of side faces 74, 76 and an end face 78. Side faces 70 and 74 are opposed to one another. Further, side faces 70, 74 in cooperation with inner face 80 form the downwardly opening central groove 62. Side face 68 along with upper face 82 form the forward groove 66 which opens forwardly as well as downwardly. In the assembled construction, the interlocked relationship between wear insert 10 and member 16 defines six discrete pairs of opposed surfaces in close abutting relation. More specifically, with legs 28, 30 received within grooves 62, 66: top wall 42 opposes upper face 82; inner wall 34 opposes side face 68; end wall 40 opposed end face 72; inner wall 36 opposes side face 70; top wall 44 opposes inner face 80; and rear wall 46 opposes side wall 74 (FIG. 5). In the preferred construction sloped surface 54 is aligned with end face 78 in a generally planar relationship. Of course other arrangements could be used.

In the preferred construction, wear insert 10 is brazed to member 16 along the six opposed surfaces noted above. In particular, the assembly is preferably fabricated by placing a plurality of solder rods 81 along end wall 40 within central gap 38 of insert 10. With the solder rods in place, insert 10 and member 16 are assembled together, as shown in FIG. 5. During the brazing process the the heated solder flows by capillary action along the opposed surfaces of insert 10 and member 16 in the directions indicated by arrows 91 and 99. Specifically, the solder flows from between end face 72 and end wall 40 and up along each side of front flange 26. In the forward direction (arrow 91), the solder flows upward between side face 68 and inner wall 34. As it reaches upper face 82, the solder flows around corner 84 and between face 82 and wall 42. In the rearward direction (arrow 99), the solder flows upward between side face 70 and inner wall 36, around corner 86, between top wall 44 and inner face 80, around corner 88 and downward between rear wall 46 and side wall 74. Preferably, the amount of solder provided permits the solder to flow to the front face 64 and inclined surface 54, but not beyond. However, an additional machining step can be employed in the event the solder seeps out from between the opposed mounting surfaces. In the preferred construction, corners 84, 86 and 88 are chamfered to ensure the free flow of the solder over all of the mounting surfaces. This interlocked construction in combination with the six discrete pairs of fixed mounting faces provides a durable construction for increased reliability. For additional security and integrity of the construction, the adjacent inserts are brazed together along their abutting sides 90, 92 (FIGS. 6 and 7).

The insert is preferably composed of a sintered combination of tungsten and cobalt. In particular insert 10 is comprised of a sintered hard metal composite of unsintered nodules of pre-blended hard metal powders of two different grades having distinctly different properties from one another. One grade has a high hardness characteristic to withstand impact forces. The other grade has a high toughness characteristic to withstand wearing forces. The composite substance possesses greater hardness and toughness characteristics than the average of the two grades considered separately. The specific fabrication and composition of the preferred material is disclosed in U.S. Pat. No. 4,956,012 to Jacobs which is incorporated by reference herein. The specially sintered composite is particularly well suited for the fabrication of inserts 10. During use of the inserts, leading face 48 primarily experiences impact forces whereas tip surface 52 primarily experiences wear forces. The preferred composite offers a beneficial compromise between toughness and hardness. Nevertheless, a variety of different materials could be used in the fabrication of wear inserts 10.

The above discussed structures and operations are merely preferred embodiments of the present invention. Various changes can be made without departing from the spirit and scope of the invention, as set forth in the claims.