Wear resistant studs for tracked vehicles

An apparatus and method for forming a wear resistant stud for a vehicle. The method comprising providing an elongate threaded stud member having a top surface, locating a body of tungsten carbide on the top surface, surrounding the body of tungsten carbide with a weld pool and while the weld pool is hot, slowly cooling the weld pool. The apparatus comprises an elongate threaded stud member having a top surface, a body of tungsten carbide on the top surface and a weld pool surrounding the body of tungsten carbide and the top surface of the stud member wherein the weld pool is slowly cooled from a hot applied state.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to studs for tracked vehicles and in particular to wear resistant studs for use in tracked vehicles and methods for forming wear resistant studs.

2. Description of Related Art

Tracked vehicles are useful in many areas where softer ground would impede the movement of wheeled vehicles. Disadvantageously, due to the lower ground pressure such tracks may suffer from reduced traction on the ground and particularly on frozen ground or ice.

Previous attempts to provide studs in tracked vehicles have not need satisfactory. In particular, many such studs have bred embedded or passed through the track and commonly formed of steel. Such steel studs however are known to wear quickly when used on pavement or asphalt are well.

Tungsten carbide is a material which is known to have excellent wear properties but is brittle and therefore not suitable for forming the entire stud. Additionally tungsten carbide is not commonly able to be welded and is therefore commonly brazed to an underlying metal. However, brazing is known to be weaker than welding.

SUMMARY OF THE INVENTION

According to a first embodiment of the present invention there is disclosed a method for forming a wear resistant stud for a vehicle comprising providing an elongate threaded stud member having a top surface, locating a body of tungsten carbide on the top surface, surrounding the body of tungsten carbide with a weld pool and while the weld pool is hot, slowly cooling the weld pool.

The slowly cooling step may comprise applying heat to the weld pool through friction. The slowly cooling step may comprise applying a rotating wire brush to the weld pool. The weld pool may completely cover the body of tungsten carbide and the top surface.

According to a further embodiment of the present invention there is disclosed a wear resistant stud for a vehicle comprising an elongate threaded stud member having a top surface, a body of tungsten carbide on the top surface and a weld pool surrounding the body of tungsten carbide and the top surface of the stud member wherein the weld pool is slowly cooled from a hot applied state

The top surface may be located on a head of the stud member. The stud member may include a bottom collar adapted to retain a track of the vehicle between the bottom nut and the head. The wear resistant stud may further comprise a top collar adapted to retain the track between the top and bottom collars.

The body of tungsten carbide may be located within a bore in the top surface of the stud member. The top surface may be located on a top member having at least two elongate threaded stud members extending substantially perpendicularly therefrom. The top member may comprise a bar extending perpendicularly between the at least to elongate threaded stud members. The top member may comprise a triangular member extending along a plane perpendicular to the at least to elongate threaded stud members.

The body of tungsten may comprise a length of tungsten carbide having a length less than the top surface. The body of tungsten carbide may have a triangular cross section. The weld pool may be slowly cooled with the use of a rotary wire brush. The weld pool may cover the body of tungsten carbide completely.

According to a further embodiment of the present invention there is disclosed a kit for forming a wear resistant member for a vehicle comprising at least one stud comprising an elongate threaded stud member having a top surface, a body of tungsten carbide on the top surface, a weld pool surrounding the body of tungsten carbide and the top surface of the stud member wherein the weld pool is slowly cooled from a hot applied state. The kit further comprises a gripping body adapted to be located on an outside surface of the track and having a bore therethrough corresponding to each stud, wherein the at least one stud is operable to be passed through a corresponding bore in the gripping body and the track so as to secure the gripping body to the track.

DETAILED DESCRIPTION

Referring toFIG. 1, continuous track8for use on a tracked vehicle is shown generally at8with at least one wear resistant stud10passed therethrough. The stud10as illustrated further inFIG. 2comprises at least one elongate threaded member12with top member14and bottom collar20adapted to retain the track8therebetween when the threaded member12is passed therethrough. The top member14includes a wear resistant body30as will be further described below.

The threaded member12may comprise any elongate member extending between top and bottom ends,15and17, respectively wherein the top member14is located at the top end15. The threaded member may comprise any suitable threaded member, however in practice it has been found that grade 8 type fasteners have been particularly useful. The threaded member12may also be selected to have a diameter to provide a suitable strength to the stud10according to known methods. In particular, it has been found that diameters between ⅜ and 1¼ inch (10 and 32 mm) has been useful although it will be appreciated that other sizes may be useful as well. The top member14may comprise a bolt head of the threaded member as illustrated inFIG. 2or other structures adapted to provide a top surface as will be further described below. The bottom collar20is threadably received on the threaded member12. As illustrated inFIG. 3the bottom collar20may be formed with a planar member22and a cylindrical portion24extending therefrom although it will be appreciated that other collar types may be utilized as well. Optionally, the threaded member12may also include a top collar21formed similar to and positioned on the threaded member in mirror to the bottom collar as well as a washer23as is commonly known. The planar member22may optionally include a plurality of key bores26extending therethrough at a position adapted to receive a key or wrench for tightening the bottom collar20on the threaded member12. It will be appreciated that any wrench type may be utilized as well such as by way of non-limiting example, hex nuts or the like. The top member14may be a separate body secured on the threaded member12or may optionally be co-formed with the threaded member12. The top member14defines a top surface16adapted to have the wear resistant body30formed thereon as will be further described below.

Referring toFIG. 3, the wear resistant body30of the stud10is formed by first locating a body of tungsten carbide32on the top surface16of the top member14. As illustrated inFIG. 3, the body of tungsten carbide32has a triangular cross section, although it will be appreciated that any other cross section, such as, by way of non-limiting example, square, rectangular or round may also be utilized. As illustrated inFIG. 4, after the body of tungsten carbide32has be located at the desired location a weld pool34may be formed therearound so as to secure the body of tungsten carbide32to the top surface16. In particular, the weld pool34is formed to surround and cover the tungsten carbide body32as well as matingly engage the top surface16. Thereafter, a rotary wire brush40is applied to the weld pool34to apply heat thereto and reduce the rate of cooling of the weld pool34. It will be appreciated that the slowed cooling of the weld pool34will assist with adhesion between the weld pool and the tungsten carbide body as well as reducing brittleness of the weld pool. After sufficient cooling, the wire brush40is removed leaving the finished wear resistant body30. It will be appreciated that the amount of time necessary will be dependant upon the size of the weld. By way of non-limiting example, it has been found that slowly cooling through the use of the wire brush to a temperature of approximately 1000 degrees Fahrenheit (500 degrees Celsius) has been useful. In practice, it has been found that a MIG welding process utilizing 0.045″ ER70S-6 welding wire and an argon/carbon dioxide shielding gas blend with a carbon dioxide content of approximately 25% has been found to be effective.

Turning now toFIG. 5, an apparatus50for breaking lengths of tungsten carbide into shorter lengths for use in the present wear resistant studs is illustrated. The apparatus50comprises a bottom support plate52and a top threaded press58adapted to apply a downward force to a length of tungsten carbide stock31located on the support plate52. The support plate52includes a gap56extending transverse to the tungsten carbide stock31at a position aligned with the threaded press58. In operation, the tungsten carbide stock31may be located at a position corresponding to the length of tungsten carbide stock31wished to be separated from the larger piece. Thereafter, the threaded press58may be turned downward to engage upon the tungsten carbide stock31and break it at the location of the gap56. It will be appreciated that other methods of forming the tungsten carbide to the desired length may also be utilized. As illustrated inFIG. 5, the press85may include a sharpened end point adapted to apply a point load to the tungsten carbide stock31above the gap56.

Turning now toFIGS. 6athrough 6d, alternative embodiments of wear resistant studs are illustrated. In particular, as illustrated inFIG. 6a, the wear resistant studs10may be passed through a t-bar70formed of first and second channel sections,72and74, respectively. As illustrated inFIG. 15, the first channel section72may be aligned with a lengthwise direction of the track8wherein the second channel section74may be transverse to the track8. Furthermore, a bar claw76may be formed with the top member14being formed by a perpendicular bar78extending between a pair of threaded members12as illustrated inFIG. 6bwherein the bar claw76may be positioned transverse or angularly relative to the track8as illustrated inFIG. 15. As illustrated inFIG. 6c, a v-shaped claw80may be also be formed with the top member formed in a triangular shape82. It will be appreciated that although a triangular shape is illustrated for the v-shaped claw, any other shape such as, by way of non-limiting example, circular, rectangular or irregular may also be utilized. Although the v-shaped claw80is illustrated inFIG. 15as having the threaded members12longitudinally along the track, it will be appreciated that other orientations such as transverse or diagonal on the track may also be utilized.

Turning now toFIGS. 7athrough 7b, alternative embodiments of wear resistant studs are illustrated. In particular, as illustrated inFIG. 7a, the wear resistant studs90include an additional nut92below the top member14so as to space the wear resistant body30further from the track8. Additionally, for use on metal tracks, the wear resistant stud94as shown inFIG. 6bmay include a self locking or nylock nut96below the top member14wherein a double nut98is provided to clamp the wear resistant stud94to the back side of the track. In operation, a user may loosen the double nuts98and position the self locking nut96to provide a desired height to the wear resistant body30. Thereafter the double nuts98may then be retightened to secure the stud to the track.

Turning now toFIGS. 8 through 10, an adjustable wear resistant stud100is illustrated. The adjustable wear resistant stud100comprises an elongate threaded member102member extending between top and bottom ends,104and106, respectively. The top end104defines the top surface108and is formed without a head portion and includes a bore110into the top surface108. As illustrated, the bore110may be a hex socket or the like as are commonly known. The body of tungsten carbide32is sized to fit within the bore110in a lengthwise configuration as illustrated inFIG. 8. Thereafter, as illustrated inFIG. 9, the weld pool34is formed around the body of tungsten carbide32and the top surface108so as to cover the body of tungsten carbide32as set out above. As illustrated inFIG. 10, top and bottom collars21and20may then be threadably located on the threaded member102as set out above such that the top edge of the top collar21is substantially aligned with the top end104of the threaded member. Thereafter, a liquid weld120or other suitable liquid adhesive may be applied to the top collar21and the weld pool so as to temporarily secure the top collar at the top position.

In operation, the stud may be secured within the track as illustrated inFIG. 11with reference to the embodiments ofFIGS. 8-10. In particular a hole6may be bored through the track8by any known means and the threaded member102passed therethrough with the top and bottom collars21and20secured to opposite ends to clamp the track8therebetween. Optionally, a bushing124, such as a disk of Teflon or other suitable material may be placed between the top collar21and the track8to reduce wear. During operation of the vehicle, it will be appreciated that the weld pool34will wear at a faster rate than the body of tungsten carbide32due to the weld pool being formed of a softer material. In such events, the tungsten carbide32will then be exposed providing a more wear resistant finish which is held in place by the remaining weld pool therearound.

With reference toFIG. 10, during a short period of operation, the liquid weld120will be abraded away permitting the top collar21to be rotated relative to the threaded member. In such case, the height of the wear resistant body30may then be raised by loosening the bottom collar20, and repositioning the top collar21at the desired height after which the bottom collar20may then be retightened. A socket130for use in loosening and tightening the top and bottom collars20and21is illustrated inFIG. 12both on to the track and also for use in assembling and torquing the top and bottom collars to the threaded member12. The socket130includes a central bore132sized to pass the wear resistant body30and the cylindrical portion24of the top or bottom collar21or20therethrough and a plurality of pins134corresponding to the locations of the key bores26.

Turning now toFIGS. 13 and 14, a rubber wheel150may also be adapted to receive the wear resistant studs disclosed above therein. In particular, the rubber wheel may be formed of first and second hubs,152and154, respectively secured together with nuts and bolts,156and158, as are commonly known. A solid rubber cylinder160may be disposed therearound having an overhang portion162adapted to extend beyond the first and second hubs152and154. The overhand portion162is selected to provide a sufficient distance for the studs to pass through such as, by way of non-limiting example, between 1 and 6 inches (25 and 152 mm). It will also be appreciated that the rubber cylinder will have a thickness selected to provide sufficient strength to maintain the studs in contact with a ground surface. In practice, it has been found that a thickness of between 2 and 4 inches (51 and 102 mm) has been useful although it will be appreciated that other thicknesses may be useful as well. As illustrated, the wear resistant studs10may be passed through the overhang portion162.