GROUND ENGAGING TOOL TOOTH TIP
A tooth tip for a ground engaging tool has an elongate body disposed along a longitudinal axis extending from a relatively wide back surface to a relatively narrow front surface. The tooth tip may also have a cavity extending from the back surface towards the front surface and a bottom surface extending between the back surface and the front surface. The bottom surface may include a front face proximate the front surface and a back face proximate the back surface. The front face and the back face may be separated by a ridge. The tooth tip may also include a scallop positioned on the bottom surface extending from a first end proximate the ridge to a second end located towards the front surface.
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The present disclosure relates generally to a tooth tip for a ground engaging tool.
BACKGROUNDMany construction and mining machines, such as excavators, wheel loaders, hydraulic mining shovels, cable shovels, bucket wheels, and draglines make use of buckets to dig material out of the earth. These buckets are subjected to extreme wear from the abrasion and impacts experienced during the digging operation. Buckets and other earth-working tools are often protected against wear by including ground engaging tools (GET). GET is typically fashioned as teeth, edge protectors, and other components which are attached to the bucket in the area where the most damaging abrasion and impacts occur. One purpose of the GET is to serve as wear material and absorb wear that would otherwise occur on the bucket. A GET is generally designed to be replaced when worn. In some arrangements, the teeth comprise one piece tips which are welded to a lip of the bucket. When these tips are worn, they are cut off the lip and replaced. In other arrangements, each tooth includes an adaptor which is either releasably attached to a nosepiece on a bucket lip, or is welded directly to the bucket lip. A tooth tip is releasably attached to the adaptor, typically with a locking pin. In this type of GET, the tooth tip is replaced when worn by removing the locking pin and sliding the tooth tip off the adaptor.
During the digging operation, the tooth tip of the GET is subject to large mechanical stresses. Rupture of the tooth tip during operation can increase the operating cost of the machine. If the tooth tip breaks and falls off the bucket during operation, it could be fed into a crusher or other processing machine and cause more expense and damage. Therefore, the tooth tip should be designed to withstand these large mechanical stresses. Typically, the tooth tip is an iron alloy component produced by casting. The casting and the subsequent heat treatment operations induce residual stresses on the tooth tip which add to the mechanical stresses during operation. In some cases these stresses may be large enough to cause failure of the tooth tip during fabrication and/or operation.
U.S. Pat. No. 5,841,033 issued to Burris et al. (the '033 patent) and assigned to the assignee of the current application discloses a process for decreasing the residual stresses and increasing the fatigue life of a component such as a tooth tip. In the '033 patent, one or more post-fabrication operations (rolling, bending, pitting, etc.) are carried out to reduce the residual stress in the component after fabrication. While the process of the '033 patent may be suitable for some applications, for other applications it may not be optimal. The present disclosure is directed to overcoming this or other limitations in existing technology.
SUMMARYIn one aspect, a tooth tip for a ground engaging tool is disclosed. The tooth tip has an elongate body disposed along a longitudinal axis extending from a relatively wide back surface to a relatively narrow front surface. The tooth tip may also have a cavity extending from the back surface towards the front surface and a bottom surface extending between the back surface and the front surface. The bottom surface may include a front face proximate the front surface and a back face proximate the back surface. The front face and the back face may be separated by a ridge. The tooth tip may also include a scallop positioned on the bottom surface extending from a first end proximate the ridge to a second end located towards the front surface.
In another aspect, a bucket for a machine is disclosed. The bucket includes an adapter coupled to the bucket and a tooth tip removably coupled to the adapter. The tooth tip may include an elongate body disposed along a longitudinal axis extending from a relatively wide back surface to a relatively narrow front surface, and a cavity extending from the back surface to a far end wall positioned towards the front surface. The cavity may be configured to removably couple with the adapter. The tooth tip may also include a bottom surface extending between the back surface and the front surface. The bottom surface may include a raised ridge region located proximately above the far end wall of the cavity, a front face extending from the ridge to the front surface, and a back face extending from the ridge to the back surface. The tooth tip may also include a scallop positioned on the bottom surface. The scallop may be an elongated depression extending along the longitudinal axis from a first end located on the ridge region to a second end positioned towards the front surface.
In yet another aspect, a tooth tip for a ground engaging tool is disclosed. The tooth tip includes an elongate body extending along a longitudinal axis from a relatively wide back surface to a relatively narrow ground engaging front surface. The tooth tip may include a cavity extending into the elongate body from the back surface to a far end wall positioned towards the front surface. The cavity may be configured to removably couple with an adapter of the ground engaging tool. The tooth tip may also include a scallop positioned on the far end wall. The scallop may be a depression that extends into the elongate body by a depth of between about 5-30% of a depth of the cavity.
The ground engaging front surface 30 of the tip 12 may have a shape and size suited for the application of the tip 12. Bucket 10 of
During operation of the bucket 10, the bottom surface 24 serves as the primary wear surface of the tip 12. The bottom surface 24 includes a front face 24a and a back face 24b that meet together at a ridge 38. The ridge 38 may be a raised region of the bottom surface 24 that may be above a far end of the pocket 22 (that is, the far end of the pocket is on the shadow of the ridge). An increased thickness T1 of material at the ridge 38 may enable the tip 12 to withstand stresses during operation. From the ridge 38, the front face 24a extends forwardly towards the front surface 30, and the back face 24b extends rearwardly towards the back surface 32. The bottom surface 24 includes a riser 36 that projects therefrom. Although the riser 36 may be positioned in either the front or the back face 24a, 24b, in some embodiments, the riser 36 may be located on the front face 24a. As is known in the art, during casting, molten metal enters a mold (having a cavity shaped like tip 12) through a down sprue. After filing the mold, a small amount of additional molten material is provided to serve as a reservoir to prevent cavities due to shrinkage. After solidification of the molten metal, and subsequent machining operations, some amount of metal remains as the riser 36. Although the riser 36 is shown as projecting from the bottom surface 24, this is not a requirement. In some embodiments, the machining operations after casting may remove substantially all the excess metal and leave the riser 36 flush with the bottom surface 24.
During casting, the molten metal at all regions of the mold may not solidify at the same time or rate. Due to differences in heat transfer rates, regions of thinner cross-section of the mold often solidify faster than regions of thicker cross-section. Due to this uneven solidification, residual stresses are induced at different regions of the solidified casting. Typically, after casting, the as-cast tip is heat treated to impart desirable wear resistant properties to the tip. Although not shown or discussed herein, the heat treatment operation may transform a layer of material on the surface of the tip 12 to a wear-resistant microstructure (such as, martensite). The heat treatment may involve heating the tip to within the austenitic range of the material, and quenching the tip 12 to form martensite. Since thicker cross-sections cool at a slower rate than thinner cross-sections, further residual stresses may be induced in some regions of the tip 12 after heat treatment. In a typical tip 12, it is known that these residual stresses (sum of the stresses induced during casting and the stresses induced during heat treatment) are especially high at the far end of the pocket 22 (that is, corresponding to the region marked A in
In order to reduce these residual stresses, the bottom surface 24 of the tip 12 may include one or more scallops 40 thereon. The scallop 40 is a depression or a basin formed on the bottom surface 24 that may serve to even out the temperature distribution at different regions of the tip 12 during casting and heat treatment. Elimination of material at the region of a scallop 40 may decrease the thickness of the cross-section in this region, and thus promote a more even temperature distribution. In general, the scallop 40 may have any size and shape. The shape of the scallop 40 may depend upon the size of the tip 12 and the application the tip 12 is used for. For instance, increasing the size and depth of the scallop 40 may decrease the thickness of the cross-section and thereby promote a more even temperature distribution and reduced residual stresses. However, reducing the thickness of the cross-section may also reduce the strength of the tip 12. Therefore, the size, shape, and distribution of the scallops 40 on the bottom surface 24 may be selected based on a trade-off between the residual stress and the strength. Further, the shape of a scallop 40 should not significantly affect the flow of molten metal into all regions of the mold during casting.
In the embodiment of
As described previously, the size and shape of the scallop 40 may be selected based on the application. In some embodiments of the tip 12, numerical simulations indicate that a substantially tear-drop shaped scallop 40 having a width “w” proximate the first end between about 50-75% of a width “W” of the tip 12, a length “1” (between the first and second ends 52, 54) between about 10-30% of an overall length “L” of the tip 12, and a thickness “t1” proximate the first end 52 between about 10-40% of a wall thickness “T1” at the base of the scallop 40 were found to reduce the residual stresses at critical regions of the tip 12 without significantly decreasing its strength. In some other embodiments, the width w, length l, and thickness t1 of between 60-70% of the width W, 20-30% of the length L, and 20-30% of the wall thickness T1, respectively, were found to be suitable.
In some embodiments, the scallop 40 may be a generally concave shaped depression on the bottom surface 24. The scallop 40 may have a curved (or a rounded) base with a varying depth, or a flat base with a constant depth. The scallop 40 may be positioned on one or both of the front and back faces 24a, 24b. Although the scallop 40 of
Although the riser 36 projects from the base 140a of the scallop 140 in the tip 112 of
In general, a scallop and a riser may be positioned at any location on the bottom surface 24 of a tip.
In addition to, or in place of, the scallops positioned on the bottom surface 24, scallops may also be positioned at other locations on tip.
Although a single scallop 440 having a width w1 and height h1 that is roughly 80% of W1 and H1, respectively, is illustrated in
The disclosed ground engaging tool tooth tip may be applied in any application where it is desired to prolong the useful life of the tooth tip. Scallops on the tool tip reduce the residual stresses that are induced in the tool tip as a result of casting and heat treatment processes. Reducing the residual stresses reduces the total stress at critical regions of the tool tip during operation and thereby reduce the likelihood of cracking of the toothtip. An exemplary method of fabricating a tool tip of the current disclosure is described below.
With reference to
Since the presence of the scallop 40 decreases the thickness of the cross-section at critical regions of the tip 12, the liquid metal in the mold will cool in a more even manner, and thereby reduce the induced residual stresses. After solidification, excess solidified metal may be removed, and the as-cast tip 12 may be heat treated. During heat treatment, the tip 12 is heated to a high temperature and then quenched. During quenching, the presence of the scallop 40 allows all regions of the tip 12 to cool in an even manner and reduce the residual stresses induced in the tip 12 a result of uneven cooling. Since the residual stresses in the tip 12 is reduced without subjecting the tip 12 to a post-fabrication stress relieving operation, the cost of the tooth tip is decreased.
As discussed previously, although a tooth tip for a bucket of an earthmoving machine is discussed herein, in general, the tooth tip may be applied to any application. For instance, an embodiment of a disclosed tip may be coupled to a ripper shank and serve as a ripper tip. It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed tooth tip. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed tooth tip. 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.
Claims
1. A tooth tip for a ground engaging tool, comprising:
- an elongate body disposed along a longitudinal axis extending from a relatively wide back surface to a relatively narrow front surface;
- a cavity extending from the back surface towards the front surface;
- a bottom surface extending between the back surface and the front surface, the bottom surface including a front face proximate the front surface and a back face proximate the back surface, the front face and the back face being separated by a ridge; and
- a scallop positioned on the bottom surface extending from a first end proximate the ridge to a second end located towards the front surface.
2. The tooth tip of claim 1, wherein the cavity extends from the back surface to a far end wall located proximate a shadow of the ridge.
3. The tooth tip of claim 1, further including a riser on the bottom surface, the riser being a feature formed as a result of a casting operation used to fabricate the tooth tip.
4. The tooth tip of claim 3, wherein the scallop has a substantially tear-drop shape.
5. The tooth tip of claim 4, wherein a width and a depth of the scallop tapers from the first end to the second end.
6. The tooth tip of claim 5, wherein the riser intersects the scallop proximate the second end such that the scallop and the riser share a surface at the second end.
7. The tooth tip of claim 3, wherein the riser is positioned substantially within the scallop.
8. The tooth tip of claim 7, wherein the riser projects upwardly from a bottom of the scallop.
9. The tooth tip of claim 1, wherein the scallop has a flat base that is parallel to the longitudinal axis.
10. The tooth tip of claim 1, wherein the tooth tip is configured to be removably coupled to a bucket of a machine at the cavity.
11. A bucket for a machine, comprising:
- an adapter coupled to the bucket;
- a tooth tip removably coupled to the adapter, the tooth tip including: an elongate body disposed along a longitudinal axis extending from a relatively wide back surface to a relatively narrow front surface; a cavity extending from the back surface to a far end wall positioned towards the front surface, the cavity being configured to removably couple with the adapter; a bottom surface extending between the back surface and the front surface, the bottom surface including a raised ridge region located proximately above the far end wall of the cavity, a front face extending from the ridge to the front surface, and a back face extending from the ridge to the back surface; and a scallop positioned on the bottom surface, the scallop being an elongated depression extending along the longitudinal axis from a first end located on the ridge region to a second end positioned towards the front surface.
12. The bucket of claim 11, wherein the tooth tip further includes a riser positioned on the front face, the riser being a feature formed as a result of a casting operation used to fabricate the tooth tip.
13. The bucket of claim 12, wherein the riser intersects the scallop proximate the second end such that the scallop and the riser share a surface at the second end.
14. The bucket of claim 12, wherein the riser is positioned substantially within the scallop.
15. The bucket of claim 11, wherein the scallop has a substantially tear-drop shape, and a width and a depth of the scallop tapers from the first end to the second end.
16. A tooth tip for a ground engaging tool, comprising:
- an elongate body extending along a longitudinal axis from a relatively wide back surface to a relatively narrow ground engaging front surface;
- a cavity extending into the elongate body from the back surface to a far end wall positioned towards the front surface, the cavity being configured to removably couple with an adapter of the ground engaging tool; and
- a scallop positioned on the far end wall, the scallop being a depression that extends into the elongate body by a depth of between about 5-30% of a depth of the cavity.
17. The tooth tip of claim 16, wherein the scallop extends from the far end wall towards the front surface.
18. The tooth tip of claim 16, wherein the scallop includes a plurality of scallops spaced apart from each other in a vertical direction.
19. The tooth tip of claim 16, wherein the scallop includes a plurality of scallops spaced apart from each other in a horizontal direction.
20. The tooth tip of claim 16, wherein the scallop includes a plurality of scallops, at least some scallops of the plurality of scallops being spaced apart from each other in a vertical direction and some scallops of the plurality of scallops being spaced apart from each other in a horizontal direction.
Type: Application
Filed: May 24, 2012
Publication Date: Nov 29, 2012
Applicant:
Inventor: Jesus Torres Gomar (Saltillo)
Application Number: 13/479,339