Patent Application
20200157781
The present disclosure relates generally to a system for securing bits, and more particularly, to a system for securing bits against rotation in an adapter board of a motor grader.
A motor grader shapes or levels the ground by forcing a tool, such as a blade, to bear against the ground over which it is driven. For some applications, the grader is configured with a series of bits instead of a blade to better cut and break up the ground. For this configuration, the blade is replaced with an adapter board securing a plurality of bits.
Some bits are optimized for use in a forward-facing orientation. For example, they may have multiple tooling surfaces optimized to cut and shape the ground when the bit is maintained in a forward-facing orientation. The tooling surfaces may be made from a hard material, such as carbide, greatly reducing the tooling surface's wear rate and thereby increasing the bit's effective life. If such a bit is allowed to freely rotate, however, the other, non-tooling surfaces of the bit contact the ground, wearing the bit out far faster than when it is maintained in a forward-facing orientation.
Adapter boards of motor graders are generally designed to constrain the bits against rotation. For example, the underside of the adapter board may have a series of machined slots interlocking with the bits. Alternatively, a plurality of holes or slots in the adapter board may have non-circular cross-sectional shapes. For example, the slots may have rectangular or square cross sections. The bits may have corresponding non-circular shanks, such that once the shanks are received within a respective hole or slot in the adapter board, they are secured in a forward-facing orientation. Snap rings may be configured to attach to the bits to prevent them from falling out of the hole or slot in the adapter board.
The machined slots on the underside of the adapter board described above may help prevent rotation of the bits, but they may become worn as the underside of the adapter board scrapes and grinds against the ground. Once the machined slots have been completely worn away, they may fail to prevent rotation of the bits. Additionally, snap ring require specialized tools to remove, increasing the difficulty associated with removing and replacing the bits.
One exemplary system for securing bits in a forward-facing orientation is described in U.S. Pat. No. 4,913,125 (“the '125 patent”) which issued to Buntin et al. on Apr. 3, 1990. The shank of the bit, which is received within the holding device, has a rectangular cross section. The holding device has a complementary shaped slot for receiving the shank. To prevent the bit from falling out, a spigot and socket is provided.
Although the system of the '125 patent may help secure bits against rotation, machining non-circular slots is generally more costly and time consuming than drilling circular holes. Additionally, the spigot-and-socket configuration involves small, intricate parts, increasing both manufacturing cost and installation difficulty.
The disclosed system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.
In one aspect, the present disclosure is directed to a bit securing system. The bit securing system includes at least two bits, and each bit includes a respective shank. Each shank includes a respective locking portion. The bit securing system includes an adapter board having at least two holes, and each respective hole of the adapter board is configured to receive a shank of a respective bit. An anti-rotation plate is configured to engage the respective locking portions of the shanks of at least two bits such that the anti-rotation plate constrains them against rotation with respect to the adapter board.
In another aspect, the present disclosure is directed to another bit securing system. The bit securing system includes an adapter board having a hole therein. The bit securing system includes a bit having a shank, and the shank has a circular portion and a locking portion. The circular portion is configured to be received within the hole of the adapter board, and the locking portion has a non-circular cross-sectional shape. The bit securing system includes a first anti-rotation plate. The first anti-rotation plate is configured to engage the non-circular cross-sectional shape of the locking portion such that the first anti-rotation plate constrains the shank against rotation with respect to the adapter board.
In another aspect, the present disclosure is directed to another bit securing system. The bit securing system includes a bit having a shank. The shank has an end with a non-circular cross-sectional shape. The bit securing system includes an adapter board having a hole configured to receive the shank of the bit therein. The bit securing system includes an anti-rotation plate configured to contact one or more of an adjacent anti-rotation plate, a second bit, and an interference surface of the adapter board such that the anti-rotation plate is constrained against rotation with respect to the adapter board. The anti-rotation plate is configured to engage the non-circular cross-sectional shape of the shank such that the anti-rotation plate constrains the shank against rotation with respect to the anti-rotation plate.
Each anti-rotation plate 18 is constrained against rotation with respect to the adapter board 14 by engaging at least two bits 12. The anti-rotation plate 18 may be configured to engage any suitable number of bits 12, however. As shown in
The bit holes 16 may be formed between the lower surface 42 and the upper surface 44 of the adapter board 14. The circular portion 26 of the shank 24 may be sized such that when the system 10 is assembled, the shoulder 20 of the bit 12 contacts the lower surface 42 of the adapter board 14. When assembled, a locking portion 28 of the shank 24 extends at least partially outside of the bit hole 16 of the adapter board 14 from the upper surface 44. The anti-rotation plate 18 is then positioned on the upper surface 44 of the adapter board 14 such that the slot 38 in the anti-rotation plate 18 receives the locking portion 28 of a respective shank 24. Additionally, in some embodiments, the locking portion 28 of the bit 12 may be sized such that the locking portion 28 is at least partially received within the bit hole 16 in the adapter board 14 when the system 10 is assembled. In other words, the locking portion 28 may be disposed at least partially within the bit hole 16 in the assembled state.
The locking portion 28, however, may have any suitable non-circular cross-sectional shape such that the anti-rotation plate 18 can engage the locking portion 28 when the system 10 is assembled and constrain the bit 12 against rotation. For example, in other embodiments, the engagement surface 30 may be curved. In other embodiments, the locking portion 28 may only have one engagement surface 30. Alternatively, the locking portion 28 may have more than two engagement surfaces 30. For example, multiple engagement surfaces 30 may define a cross-sectional shape of the locking portion 28 that is triangular, square, rectangular, or pentagonal, etc.
The engagement surface 30 may be formed using any suitable method known in the art. For example, the engagement surface 30 may be formed by removing material from the shank 24. When first formed, the shank 24 may have a circular cross section along its entire length. One or more engagement surfaces 30 may then be formed by removing a portion of the shank 24 using any suitable technique. For example, the shank 24 may be machined, ground, cut, etched etc. to form one or more engagement surfaces 30 in the locking portion 28. Any other suitable manufacturing technique may be used to form a locking portion 28 having a non-circular cross sectional area. For example, the bit 12 may be cast using a mold. Alternatively, various portions of the bit 12 may be formed separately and welded together.
The circular portion 26 is configured to be received within a respective bit hole 16 of the adapter board 14. For example, both the circular portion 26 of the shank 24 and the bit holes 16 of the adapter board 14 may be sized such that circular portion 26 can be easily inserted and removed from a respective bit hole 16. For example, the circular portion 26 of the shank 24 and the bit holes 16 of the adapter board 14 may form a sliding or running fit.
The anti-rotation plate 18 of the embodiment illustrated in
When the anti-rotation plate 18 is installed as shown in
The embodiment illustrated in
In the embodiment illustrated in
The embodiment illustrated in
Referring again to the embodiment illustrated in
In another embodiment, the system 10 may be configured to only allow installation of the bits 12 in a forward-facing orientation. This configuration is not shown in the figures. For example, a portion of the outer edge 39 of the anti-rotation plate 18 that is opposite the interference surface 40 may include a protrusion, such as a tab. The protrusion and interference surface 40 may prevent the anti-rotation plates 18 from being installed such that the bit 12 faces backwards once installed. Alternatively, the outer edges 39 of the anti-rotation plates 18 may be configured to interlock with the outer edges 39 of adjacent anti-rotation plates 18 such that the anti-rotation plates 18 must be installed facing the same direction. The anti-rotation plate 18 and bit 12 may be similarly configured to prevent assembly with the bit facing any direction except forward. For example, the pair of engagement surfaces 30 of the locking portion 28 may be disposed in a non-parallel configuration. The slot 38 of the anti-rotation plate 18 may have a corresponding shape. Thus, the system 10 may be configured to prevent assembly with the bits 12 facing any direction except the forward direction 15.
The forward direction 15 refers to the movement of the motor grader when driven forward. In the embodiments illustrated in
The disclosed bit securing system 10 finds potential application in any device requiring a bit 12 to be secured in a particular orientation. The disclosed bit securing system 10 finds particular applicability with motor graders having adapter boards 14 securing bits 12. Assembly of the bit securing system 10 will now be explained.
One embodiment of the system 10 is shown in
The disclosed system 10 easily facilitates replacing worn bits 12. As they become worn, the bits 12 can be individually replaced, if necessary, by reversing the assembly process described above. Unlike snap rings, the linchpins 32 used in the disclosed embodiments can be easily removed by hand without specialized tools.
The disclosed system 10 also constrains the bits 12 against rotation after the lower surface 42 of the adapter board 14 has become severely worn. As the adapter board 14 and bits 12 are forced against the ground, terrain inconsistencies such as rocks or gravel, may scrape and grind against the lower surface 42 of the adapter board 14. As the lower surface 42 of the adapter board 14 is worn down by these abrasions, the anti-rotation plate 18 and the locking portion 28 of the bit 12 remain unaffected because they are disposed on the upper surface 44 of the adapter board 14. Additionally, as the adapter board 14 becomes severely worn, the abrasions may reduce the thickness of the adapter board 14 as measured between the lower surface 42 and the upper surface 44. Despite the reduced thickness of the adapter board 14, however, the anti-rotation plates 18 may constrain the bits 12 against rotation by engaging the locking portions 28 of the bits 12. As explained in the previous section, the locking portions 28 may be partially received within the bit holes 16 below the upper surface 44 of the adapter board 14. Thus, once the thickness of the adapter board 14 is reduced, a segment of the locking portions 28 which was previously received within the bit holes 16 may now extend above the upper surface 44 such that the anti-rotation plate 18 may still engage the locking portions 28 despite the reduced thickness of the adapter board 14. This may extend the useful life of the bits 12.
The disclosed system 10 may also provide increased versatility. As explained in the previous section, the adapter board 14 may be secured to the motor grader such that the interference surface 40 is not perpendicular to the forward direction 15 of the motor grader's movement. For example, the adapter board 14 may be secured at an angle such that dirt and rocks dislodged by the bits 12 are pushed to one side of the adapter board 14, similar to the operation of a snow plow. A set of appropriately configured anti-rotation plates 18 may be selected depending on the desired angle of the adapter board 14 such that the bits 12 are still secured facing the forward direction 15. Because the bit holes 16 in the adapter board 14 are circular, the anti-rotation plates 18 may be configured to secure the bits 12 at any suitable angle with respect to the adapter board 14.
Lastly, the disclosed system 10 may be manufactured using simple and inexpensive processes. For example, a simple drilling process may be used to form the circular bit holes 16 in the adapter board 14. The disclosed system 10 does not require any non-circular slot 38 in the adapter board 14 to secure the bits 12. The locking portions 28 of the bits 12 may also be easily formed by removing material from an initially cylindrical shank 24 using any suitable technique, such as machining, cutting, grinding etc. The anti-rotation plate 18 may also be easily formed using any suitable technique including forming a flat plate and then punching or cutting the slot 38. Alternatively, the anti-rotation plate 18 may be cast in a mold.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed system without departing from the scope of the disclosure. Other embodiments of the system will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed bit securing system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
This application is a division of U.S. patent application Ser. No. 15/864,171, filed Jan. 8, 2018, which claims the benefit of priority of U.S. Provisional Patent Application No. 62/444,179, filed Jan. 9, 2017. The contents of the above-referenced applications are expressly incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 62444179 | Jan 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15864171 | Jan 2018 | US |
| Child | 16748961 | US |
