HK1074657B - Assembly for securing a wear member - Google Patents

Description

Device for fixing wear-resistant component

Technical Field

The present invention relates to an apparatus for securing a wear member to excavating equipment, and in particular, to an apparatus for attaching an adapter to a dredge cutterhead.

Background

Dredge cutterheads are used to excavate soil under water, such as river beds. An example of a dredge cutterhead is shown in figure 17. Generally, a dredge cutterhead includes a plurality of arms 11 that extend from the base ring 16 to the hub 23(a hub). The arms are equally spaced around the base ring 16 and are formed with a broad spiral (a) around the central axis of the cutterhead. Each arm carries a series of spaced apart teeth 12 for drilling into the ground.

In use, the cutterhead is rotated about its central axis to excavate earth. To dig the desired ground track, the cutterhead is moved side-to-side and forward. Due to the waves and other movements of the water, it will also be possible for the cutterhead to move up and down and to periodically strike the bottom surface. As a result of this unique cutting action, the teeth on a dredge cutterhead are subjected to strong transverse and axial loads, as well as strong impact traction loads, urging the teeth upward, downward, and laterally. Strong lateral loads on the tooth can also result from the operator's inability to see the ground excavated underwater. Unlike other excavators, such as front-end loaders, the operator of a dredge cutterhead is unable to efficiently guide the cutterhead along a path that best suits the terrain to be excavated.

Due to the rotary digging action of the cutterhead, each tooth will penetrate the ground at a frequency of 30 times per minute, and for mining teeth, about 1 time per minute. It is therefore desirable for these teeth to be easily removable and installable to reduce downtime of the cutterhead. As with wear arrangements for excavating equipment, dredging teeth also include a plurality of integrally connected components in order to reduce the amount of material that must be replaced, i.e., only the worn components need to be replaced.

In the example shown in fig. 17, each tooth includes a base 18, an adapter 13, a point or tip 17, and a lock 29. The base 18 is cast at a particular location on the arm 11 and is oriented to maximize the digging action. The adapter 13 includes a rear end 22 which is received in a socket 14 formed in the base 18 and a forwardly projecting protrusion 15 to hold the tip 17. A removable lock 29 is provided to facilitate replacement of point 17 at a desired frequency. The adapter is retained in the socket by a large fillet weld (a) around the periphery of the rear end 22. In other known dredge cutterheads 1, the adapter 2 is bifurcated to form a pair of legs that are configured to wrap around the arms 3 (fig. 18). These adapters are welded directly to the arm without a base member.

Although frequent replacement of the tooth tips is required in a dredge cutterhead, the adapters still wear out and need to be replaced periodically. However, even replacing a single adapter on a dredge cutterhead is a lengthy process. The welded adapter must be cut off with a welding saw. The portion of the arm and base damaged by the removal of the adapter must then be repaired or refurbished. Finally, a new adapter is welded into place. This process typically requires 10-12 man-hours per adapter. Therefore, even if only a single adapter is replaced, the dredging work is inevitably delayed for a long time. Furthermore, in view of such long delays, the operator will often wait until several adapters need to be replaced to bring the cutterhead out of service. Thus, the actual delay in operation is typically longer. In fact, for a typical cutterhead having 50-60 teeth, the entire cutterhead refurbishing process requires more than 600 man-hours. To avoid long periods of dredging time, most dredging operations are equipped with three or four cutterheads, so that the entire cutterhead can be replaced when one or more adapters need to be replaced, the cutterhead needs to be refurbished, or the cutterhead breaks. However, the cutterhead is very expensive. Maintenance of excess cutterheads that are used only when the cutterhead in use requires servicing is a waste of resources.

Disclosure of Invention

In order to solve the foregoing technical problem, according to one aspect of the present invention, there is provided an apparatus for mounting a wear member on excavating equipment, comprising: a base adapted to be secured to a digging portion of an excavator, the base including a convex front bearing surface curved about two perpendicular axes and a rear facing bearing surface; a wear member comprising: a concave abutment surface curved in both horizontal and vertical directions to abut the front bearing surface; an opening having a load-bearing wall; and a working portion projecting forward; and a lock received in the opening to oppose the rear facing bearing surface and the bearing wall of the opening to prevent the wear member from loosening.

According to another aspect of the present invention, there is provided a wear member for attachment to an excavator to which a base is fixed, the wear member comprising: an opening for receiving a lock; a working portion projecting forward; and a rearwardly facing abutment surface adapted to abut the bearing surface of the base and defining a concave portion that curves in both the horizontal and vertical directions.

According to a further aspect of the present invention, there is provided a wear member for attachment to an excavator to which a base is fixed, the wear member comprising: a rear mounting portion, a front working portion, a rearwardly facing abutment surface adapted to abut the load bearing surface of the base, the abutment surface being concave and curved in both a horizontal and vertical direction, and an opening for receiving a lock, the opening having a front wall portion and a rear wall portion, the rear wall portion being adapted to oppose the lock to secure the wear member to an excavator, the rear wall portion being concave and curved.

Further in accordance with yet another aspect of the present invention, there is provided a base for attaching a wear member to excavating equipment, the base comprising two generally vertically curved forwardly facing convex bearing surfaces for abutment with complementary abutment surfaces on the wear member, and a rear mounting block adapted to be secured to the excavating equipment.

According to a further aspect of the present invention there is provided a base adapted to be secured to an excavator for mounting a wear member, the excavator having an excavating edge, the base including a coupling structure for receiving and supporting a wear member; and a body having a first convex bearing surface facing the front side for abutting the complementary surface of the wear member and a second convex bearing surface facing the rear side for abutting the lock.

According to a further aspect of the present invention there is provided a lock adapted to secure a wear member to a base, the wear member having an opening for receiving the lock, the lock comprising a front side member, a rear side member, a resilient member located between the front and rear side members, and an actuator, the rear side member comprising a rear side surface for abutting a rear wall of the opening in an adapter, the actuator comprising a front side surface for abutting a rear bearing surface of the base, the actuator being operable to move the front and rear bearing surfaces away from each other to secure the coupled condition of the adapter and tab, and the actuator being further operable to pull the front and rear side members together to compress the resilient member.

According to yet another aspect of the present invention, there is provided a dredge cutterhead comprising a base member and a plurality of forwardly projecting spiral arms, each arm including a forward edge having a plurality of spaced locating formations, each locating formation having a identically shaped rigid fixed locating member which is machined to positively mate with a digging assembly to properly set the position of said digging assembly on the arm.

In accordance with yet another aspect of the present invention, a dredge cutterhead is provided, including a base member, a hub, and a plurality of spiral arms extending between the base and the hub, each arm including a leading edge having a plurality of spaced apart bases secured to the arm along the leading edge, a plurality of teeth attached to the bases, each tooth including at least one tooth member, and a plurality of latches for releasably securing the tooth member to the base.

According to yet another aspect of the present invention, there is provided a method of attaching an adapter to a dredge cutterhead in a suitable position, comprising: providing a dredge cutterhead with a plurality of forwardly projecting spiral arms, each arm having a forward edge and each forward edge including a plurality of spaced apart locating structures, each locating structure having the same configuration; providing adapters at said locating formations for attachment to said arms, each of said adapters including a forwardly projecting projection and a coupling formation mateable with each of said locating formations; matingly engaging a coupling structure on each adapter with one of the positioning structures to properly position the adapter relative to the arm; and securing each adapter in place on the arm.

More specifically, in one aspect of the invention, the adapter is mechanically attached to the arm for ease of installation and removal. The adapter is held to the base of the arm by only one mechanical feature without the need for welding the adapter. In a preferred construction, the base and the adapter are formed with complementary coupling structures to prevent the adapter from being released from the base in a direction other than the release direction. A removable lock is used to prevent the adapter from being undesirably released from the base in the release direction. With a mechanical attachment means, the adapter can be easily replaced by simply removing the lock and moving the adapter in the release direction. In this case there is no need to cut the weld, to refurbish the base and arm, and to weld again. The mechanically attached adapter according to the present invention can be replaced in as little as 10 minutes, as opposed to 10-12 man-hours required to replace a welded adapter. This is a surprising improvement, not only significantly reducing the downtime of the cutterhead, but also making it possible to avoid equipping a dredging site with a completely redundant cutterhead. Thus, instead of requiring three or four cutterheads as is typical at a dredging site, only two or three cutterheads may be required.

In a preferred construction of the invention, the adapter includes a generally T-shaped slot for receiving a complementary tongue on the base and an opening for receiving a lock. When inserted into the opening, the lock opposes the walls of the base and the opening to prevent the tongue and slot from loosening and thereby retain the adapter on the base.

Common to adapters in various excavators, such as front end loaders, is mechanical attachment to the excavating bucket. For example, U.S. patent No.5653048 discloses an adapter with a T-shaped slot for receiving a T-shaped projection welded to the lip of an excavator bucket. A lock is fitted in an opening in the top of the adapter to prevent the adapter from sliding off the lip. A bearing surface is formed at the forward end of the tab to provide axial support to the adapter. While this configuration works well for supporting the adapter on the excavating bucket, it is not well suited for use on a dredge cutterhead.

In an excavator bucket, the teeth are subjected primarily to axial loads as the bucket is driven forward in the ground. However, as previously mentioned, the teeth on a dredge cutterhead are subject to strong and frequent lateral loads due to the manner in which the cutterhead operates. In the aforementioned us patent No.5653048, the adapter 4 is slid onto the projection 5 with a slight lateral clearance to facilitate assembly. The application of a large side load L on the tooth point 6 will tend to cause the adapter to rotate about the received tab to the extent of the clearance defined between the components (fig. 16). This rotation of the adapter results in drag forces R1-R4 and high stresses are created by the substantially "point" contact at the corners of the device. Although true "point" contact is not possible, the term is used to indicate that a large force is applied over a relatively small area. In particular, the large forces R2, R3 exerted on the front portion of the base and on lock 7 in the form of "points" create particularly high stress values on the assembly. Accordingly, such high stress values can result in greater wear of the components at these locations and shorten the useful life of these components. Increased wear also increases the clearance space, which can lead to rattling of the assembly during use. This rattling of the parts further accelerates the wear of these parts.

In conventional excavation work, such as with a front end loader, fine sand may be squeezed between the adapter and base, reducing or eliminating rattling even when wear has created a large gap between the components. However, during dredging operations, water will flush fine sand into and out of the gap and prevent the fine sand from being deposited between the parts. Since the clearance between the components is generally maintained during dredging operations, mechanically attaching the adapter to a boss on the dredge cutterhead using a known configuration will continue to produce rattling on the boss and repeatedly apply large loads in point contact along the front and rear of the adapter. Furthermore, since the fine sand is constantly flushed by water into and out of the gaps between the parts, the fine sand will actually act as an abrasive substance acting on the parts to further increase the wear of the parts. Therefore, adapters for dredging operations cannot be mechanically attached to the arms on the dredge cutterhead as before.

However, these disadvantages are overcome in the present invention so that the adapters in the dredging teeth can be mechanically attached to the arms. In particular, the front of the base is bent and brought into contact with a complementary abutment on the adapter. Thus, the curved shape of the bearing surfaces enables these surfaces to be in substantially full direct contact with each other when the adapter is pushed in a rotational manner by a side load. This full contact scheme greatly reduces the stress experienced at the corners of the component as opposed to point contact. Rather than having very high loads applied substantially as point contacts, the loads are spread substantially over the entire load bearing surface to substantially reduce stresses in the component and, correspondingly, significantly extend the useful life of the component.

In a preferred construction, the arcuate bearing surfaces form a spherical portion to maintain substantially full contact between the bearing surfaces of the adapter and base under horizontal and vertical lateral loads. In addition, the rear bearing surface of the base and the front of the lock are also preferably provided with similar arcuate surfaces to similarly maintain substantially full contact between the lock and the base. Preferably, the radius of curvature of the bearing surface originates from the same point at the front and rear of the adapter.

In another aspect of the invention, a wear member for use with excavators other than dredge cutterheads may also benefit from incorporating the curved bearing surfaces described above with respect to the adapters.

In yet another aspect of the invention, the lock is configured to secure the connection between the base and the adapter. The fastened device reduces rattling and thereby extends the useful life of the teeth. The aforementioned U.S. patent No.5653048 discloses a lock with a threaded spigot for securing an adapter to a boss. Nevertheless, the stresses and strains of the digging operation constantly loosen an originally fastened device, so that the adapter will still shift and rattle on the base, resulting in increased wear, especially when high frequency stabbing and tooth loads on the dredge cutterhead change. Also, with a loose device, there is no way to prevent the assembly from rattling during use in an aqueous environment.

Thus, in accordance with yet another aspect of the present invention, the lock further includes a resilient member that cooperates with an actuator to maintain a tight fit between the adapter and the base, even after loads have caused wear between the components. The elastic member is sandwiched between a pair of rigid members. The actuator first pulls the adapter into a tight fit with the base and pulls the rigid members together to compress the resilient members. As slack begins to develop in the device due to wear, the resilient member stretches to reduce any shifting or rattling of the adapter on the base and thereby maintain a tight fit between the two components. The rigid member also preferably has at least one stop for preventing the resilient member from being over-compressed. In this way, the rigid member first forms a rigid lock which is tightly arranged between the adapter and the base and also prevents permanent deformation of the internal elastic member due to overloading.

As previously mentioned, the arms on a dredge cutterhead have a broad spiral configuration. Finally, the teeth each project from the arm in a unique orientation to maximize the digging action. Since the teeth are mounted on the arm in different orientations, care must be taken to ensure that each adapter is properly positioned on the arm. This additional positioning step further increases the time required to install a new adapter in a known cutterhead. In the example shown in fig. 17, a resin is poured into the recess to harden around the first installed adapter, thereby forming a recess suitable for properly orienting the adapters successively for dredging operations. In any event, this design still requires careful, time-consuming steps to first properly place the adapter on the arm, with the additional work of pouring and curing the resin.

As can be appreciated, since there is no guidance on the base during the direct welding of the adapters to the arms, such as shown in FIG. 18, there is little ability to properly position each adapter to maximize digging efficiency. Furthermore, the arms on a dredge cutter do not have a uniform configuration as they extend from the base ring to the hub. To avoid the cost and inconvenience of having to make specially shaped adapters to fit properly at each designated location along the arm, adapters are made to fit universally on the arm. Thus, the fit-up is generally slack, thereby making it even more difficult to properly position the adapter for welding. Excavation efficiency is thus often lost to improper installation of these teeth on a dredge cutter.

In yet another aspect of the invention, the arm is formed with a plurality of spaced locating features along the front edge of the arm to properly locate the teeth in the desired orientation. The locating structures all have the same configuration, although their orientation relative to the surrounding arm profile may be varied to properly locate each tooth for a particular position along the arm. In one aspect of the invention, a separable base member is provided with a complementary coupling structure to mate with the locating structure to properly support and locate the adapter on the arm. Finally, each base may have the same shape regardless of their intended mounting position along the arm. Furthermore, these bases are suitable for positioning on a dredge cutterhead in a convenient, accurate and quick manner. In an alternative embodiment of the invention, a weld-on adapter includes a coupling structure to mate with a locating structure provided on the arm so that the weld-on adapter can be easily secured in place on the arm. Like the base of the present invention, these adapters can all be made to have the same shape and be easily positioned correctly, regardless of their intended mounting position along the arm.

Drawings

FIG. 1 is a front exploded perspective view of an attachment device according to the present invention.

Fig. 2 is a perspective view of a base in accordance with the present invention, incorporating a virtual ball.

Fig. 3 is a plan top view of the base.

Fig. 4 is a side elevational view of the base.

Figure 5 is a perspective view of a portion of an arm on a dredge cutterhead in accordance with the present invention.

FIG. 6 is a top perspective view of the base on the arm.

Fig. 7 is a rear perspective view of an adapter in accordance with the present invention.

Fig. 8 is a side elevation view of the adapter.

Fig. 9 is a top plan view of the adapter.

Figure 10 is an exploded perspective view of a lock in accordance with the present invention.

Figure 11 is a side elevational view of the lock.

Figure 12 is a top plan view of the lock.

Figure 13 is a perspective view of the lock.

Figure 14 is a cross-sectional view of the lock taken along line XIV-XIV of figure 13.

Fig. 15 is a schematic top view of a tooth according to the present invention under side load.

FIG. 16 is a schematic top view of a prior art tooth under side load.

Figure 17 is a perspective view of a prior art dredge cutterhead.

Figure 18 is a perspective view of another prior art dredge cutterhead.

Figure 19 is a perspective view of a welded adapter mounted on a dredge arm in another embodiment.

Fig. 20 is a side view of an alternative weld adapter.

Detailed Description

The present invention pertains to a device for securing a wear member to an excavator. The present invention is particularly suited for mounting a tooth on a dredge cutterhead because, in the preferred construction, the tooth is well able to withstand the heavy lateral loads typical of dredging operations and reduces rattling of the components. Nevertheless, the tooth according to the invention can also be used with other excavators. In addition, other wear members used in excavating equipment, such as shrouds, may also be mounted using the present invention.

In accordance with the present invention, a tooth 30 includes a base or foot 32, an adapter 34, a tip (not shown), and a lock 36 (fig. 1). These tooth assemblies will at times be described in relative terms, such as up and down, although the operation of the dredging apparatus will cause the teeth to assume many different orientations. These directions are for illustrative purposes only and will generally be understood with respect to the orientation in fig. 1.

In the preferred construction, the base 32 has a lower leg 38, a front body 40 and an upper leg 42, generally in a U-shaped configuration (FIGS. 1-4) wrapped around the front edge 44 of an arm 48 of the cutterhead for reinforcement. The base is preferably a one-piece cast product that is secured to the arm by welding, but may be mechanically attached or constructed as a modular component. Alternatively, the base may be fixed to the arm as a structure that is cast as an integral part of the arm (not shown).

Lower leg 38 extends only a short distance along the underside 47 of arm 48, although it may be omitted or provided with an extension. Upper leg 42 extends rearwardly along upper side 55 of arm 48 and includes a coupling structure 56 for securing the adapter. Since the lower or inner side 47 of the arm of the dredge cutterhead is relatively inaccessible, the coupling structure is preferably formed on the upper or outer side 55 of the arm. However, other configurations are possible. For example, the legs may be inverted on the arms, or a coupling structure may be provided on both the upper and lower sides of the arms. The legs 38, 42 and body 40 cooperate to define an inner surface 54 facing the arm. To facilitate efficient welding of the base to the arm, the inner surface 54 is machined to substantially conform to the contour of the portion of arm 48 opposite to which it faces. The base is welded to the arm along substantially its entire periphery to securely hold the base to the cutterhead.

Upper leg 42 extends along upper side 55 of the arm toward the rear of body 40 to define a coupling structure 56 for securing the adapter. The coupling structure 56 is preferably an axial T-shaped tongue 57, the tongue 57 being a sliding fit with a complementary shaped structure 58 on the adapter 34. However, other structures with at least one laterally extending shoulder may be used to couple the adapter to the base. For example, the coupling structure 56 could be formed as other generally T-shaped tongues, such as dovetail tongues and other tongues that widen laterally in a symmetrical manner, other asymmetrically-shaped tongues, or slots having a T-shape, dovetail shape, or other shape. In any event, the upper leg preferably extends first upwardly above the body 40 to allow the adapter to slide through the body and couple with the tongue. The rear end wall of upper leg 42 defines a rear bearing surface 60 adapted to engage lock 36. As discussed more fully below, the rear bearing surface is preferably curved and more preferably defines a convex spherical portion (FIG. 2). Nevertheless, a flat rear bearing surface may also be used, albeit with reduced benefits.

Body 40 projects forwardly from forward edge 44 of arm 48 to resist forces exerted on tooth 30 during use. In the preferred construction, the body includes side walls 50, 52, top and bottom walls 64, 66, and a front bearing surface 68. The front bearing surface 68 is convexly curved to maintain substantially full surface contact with a complementary surface on the adapter during lateral loading of the tooth, as discussed more fully below. In the preferred construction, the front bearing surface 68 defines a convex spherical portion (shown in phantom in FIG. 2) to receive transverse loads in any direction, such as side loads, upward loads, downward loads, or any virtual load that would exert a transverse force against the longitudinal axis 69 of the tooth. The bearing surface 68, however, will be formed with a surface that is curved in both the horizontal and vertical directions, but is not spherical. In such a configuration, the radius of curvature in either or both bending directions may be fixed or may vary. Furthermore, the bearing surface 68 will only carry one curved shape in one direction, although the benefit is reduced. For example, the bearing surface 68 will only flex in a horizontal or vertical direction or in any particular direction desired. However, when bending occurs in only one direction, the desired full surface contact can only be maintained for lateral loads in substantially the same direction as the bending portion of the load bearing surface.

The radius of curvature defining the bearing surface 68 depends on the relative clearance that exists between the base and the adapter. For example, a gap is formed between the parts to ensure that the adapter can be coupled to the base, particularly along the coupling structure. When a transverse load is applied to the tooth point, the adapter will rotate until the gap closes at diagonally opposed corners along the sides, forming a junction against the transverse load. If the gap between the base and adapter is the same along the front and rear ends of base 32, the center of rotation of the adapter will be approximately at the center point M of base 32 (i.e., the center point between bearing surfaces 60, 68). However, if the gap at one end is small compared to the other end, the center of rotation will be closer to the end with the smaller gap, depending on the amount of imbalance between the parts, i.e., the greater the imbalance of the gap, the greater the offset of the center of rotation toward the end with the smaller gap. In a preferred configuration, the center of rotation is used as a virtual center point of the radius of curvature. As can be appreciated, the difference in the gap along the sides will be different than the gap along the top and bottom of the base and adapter. In this configuration, the curvature in the horizontal direction is preferably different from the curvature in the vertical direction so as to correspond to the difference in the different clearances.

In a preferred construction, as shown in FIG. 2, the rear bearing surface 60 is curved in the same manner as the front bearing surface 68, although they could be curved in a different manner. Thus, the rear bearing surface may be modified (e.g., curved in one or more directions) in the manner discussed above with respect to the front bearing surface 68. Preferably, the rear bearing surface 60 and the front bearing surface 68 are defined by radii of curvature originating from the same point, which coincides with the center of rotation of the adapter. However, since the component will inevitably deflect under heavy loads, there will be some deviation in the points defining the radii of curvature for the front and rear bearing surfaces. Also, the rear bearing surface 60 may have a very different starting point for defining the radius of curvature, or may even be flat, although such a configuration would impose higher stresses on the lock and rear portion of the base. Thus, the front and rear bearing surfaces may not only have the same curvature, but may also simply have corresponding curvatures, i.e. the radii of curvature originate from the same point, although they may each have different lengths. For example, if the center of rotation of the adapter is closer to the rear end than to the front end as previously described, the rear bearing surface 60 will preferably have a smaller radius of curvature than the front bearing surface 68.

The front edge 44 of the arm 48 preferably carries a plurality of spaced apart locating formations 65 for mounting the digging tooth. In a preferred embodiment, each of the locating structures includes a locating projection 70 (FIG. 5) that projects from a recess 71. In the preferred construction, each locating protrusion is cast as part of the illustrated arm in a mold using a specially shaped core. The core is placed in a mold in the desired orientation for proper positioning of the teeth on the arms. In this way, there is no difficulty in positioning the adapter on the arm. The locating projections 70 cast on the arms 48 have provided the desired orientation for the teeth.

In the preferred construction, the locating projection projects from a recess 71 formed in the forward edge of arm 48. The grooved surface 72 on the bottom of the groove opposite the inside edges 53, 54 of the side walls 50, 52 of the base body preferably leaves a slight gap. This gap also allows the operator to more easily cut the base from the arm as desired. Preferably, a space 73 exists between the outer surfaces 74, 75 of the side walls 50, 52 and the inclined surface 76 for the welding operation. The adapter includes a coupling structure 78 that interacts with the positioning structure 65 to properly position the digging tooth to maximize digging efficiency. In this configuration, the body 40 of the base 32 defines a slot 77, the slot 77 matingly receiving a locating projection 79 to properly locate and support the base on the arm. The side surfaces 79 and free end surfaces 80 of the projections 70 fit on complementary surfaces defining the slots 77 to properly locate the teeth on the arms and provide support for the lugs in addition to welding. To this end, the projection 70 preferably has a distinct forward extension. In one preferred construction, the protrusions extend about 1.50 inches beyond the grooved surface 72 and are in the range of 0.75 to 2.25 inches. Nevertheless, fewer or more tab extensions may be utilized.

A wear member in the form of an adapter 34 (fig. 1 and 7-9) has a rear portion 86 mounted on the base 32 and a front portion 88 (not shown) for holding a point or tip. In the preferred construction, the front portion includes a forwardly projecting projection 90, the projection 90 being received in a slot in the tip. The projection may have any configuration for mounting a point. In this embodiment, the front portion further includes a slot 92 for receiving a locking pin (not shown) to secure the tip to the adapter. The rear portion 86 includes an upper leg 94, a lower leg 96 and a middle portion 98. The lower leg 96 of the adapter 34 overlies the bottom wall 66. The rear ends 97 of the legs 96 are opposite the front wall 101 of the base so that under extreme loads the wall 101 acts to resist deflection of the adapter on the base. The upper leg 94 extends rearwardly to overlie the top wall 64 and the upper leg 42 of the base 32. The upper leg of the adapter 34 includes a coupling structure 58 adapted to mate with the coupling structure 56 on the base 32. Thus, the coupling structure on the adapter 34 may vary in the same manner as the coupling structure for the base 32. In the preferred embodiment, the upper leg 94 includes a T-shaped slot 103, the slot 103 matingly receiving the T-shaped tongue 57. The T-slot 103 is open along the inner surface 104 and is located on the rear wall 106 of the upper leg 94 to facilitate receipt of the tongue 57. Ribs 107 are preferably formed along the inside edge 108 of the central portion 98 for added strength to resist breakage during use (fig. 1, 7 and 8).

The intermediate portion 98 of the adapter includes an interior recess 109, the interior recess 109 having an abutment or abutment surface 105 adapted to abut the front bearing surface 68 of the base 32. Thus, the abutment 105 and the bearing surface 68 each preferably define a spherical portion having substantially the same radius of curvature, although the curvature may vary to some extent due primarily to the deflection of the components under heavy loads. As previously mentioned, the preferred shape of the abutment 105 and bearing surface 68 is defined by a radius of curvature that depends on the gap between the forward and rearward ends of the adapter and base. In the most preferred configuration, the gap between the base and the adapter is consistent from front to back along the sides and top and bottom so that the curved bearing surfaces 68, 105 each define a spherical portion. The actual required size of the radius of curvature defining the spherical portion will depend on the actual size of the gap and the component. In general, the radius of curvature defining the surfaces 68, 105 is preferably no greater than the length of the base 32 (i.e., the distance between the rear bearing surface 68 and the front bearing surface 68) to avoid having an overly broad arc.

As shown in fig. 15, the side load L1 tends to cause the adapter 34 to rotate relative to the base 32 about a center of rotation C. The radii of curvature defining bearing surfaces 68 and 105 originate from the same center of rotation. Due to the mating arcuate configuration between the abutment 105 and the bearing surface 68, these surfaces remain substantially in full surface contact with each other. Thus, no force is applied in the axial direction as in a point contact, resulting in permanent wear of the parts. Instead, the axial load is distributed substantially over the entire abutment 105 and bearing surface 68 to substantially reduce stresses in the components. Ultimately, the higher stresses associated with the resultant forces R2, R3 (fig. 16) are substantially eliminated.

The adapter 34 also includes an opening 110 (fig. 1 and 7-9) in the rear of the upper leg 94. In the preferred construction, the opening 110 is generally rectangular in configuration with a curved front wall 113 and a curved rear wall 115. However, it is not necessary that the walls be curved or that the opening be of generally rectangular configuration. Rather, the opening may be virtually any shape that is capable of receiving the lock and, accordingly, securing the adapter to the base. If adapter 34 becomes misaligned during use, lock 36 will tend to move with the adapter. Thus, there is generally no significant offset between the lock and adapter, and thus no excessive wear therebetween. Rear wall 115 preferably includes an aperture 117 extending through rear end 106 of upper leg 94 to receive the adjustment mechanism of lock 36. However, the aperture 117 may have various other shapes or may be omitted if no adjustment means is used or an adjustment means is used that does not take advantage of the space provided by the aperture 117.

Lock 36 is adapted to be received in opening 110 (fig. 1 and 10-14). In the preferred construction, lock 36 is generally rectangular in configuration with a curved front wall 123 and a curved rear wall 125 to match the configuration of opening 110. While deflection is less likely to occur between the adapter and lock, the curved walls 115, 125 help to mitigate any wear in the event of deflection. However, lock 36 may have various shapes in the same manner as discussed above with respect to opening 110.

In the preferred construction, the lock 36 includes an outer member 127, an inner member 129, a resilient member 131 and an actuator, preferably in the form of a screw 133. The outer part 127 defines a cavity 134 for receiving the inner part 129 and the resilient member 131. Generally, the outer member 127 is generally C-shaped, including a base wall 135, a top wall 137, and a bottom wall 139. A pair of lips 141, 143 extend from the top wall 137 and the bottom wall 139 toward each other to restrain the inner part 129 and the resilient member 131 in the cavity 134. Base wall 135 includes a hole 136 for receiving screw 133. The inner part is also generally C-shaped in configuration with a central wall 147 and two side walls 149. The two C-shaped components fit together to define a box shape overall. In the preferred curved configuration, side walls 149 form an obtuse angle with respect to intermediate wall 147 to mate with side edges 150 of outer member 127. An internally threaded projection 151 extends rearwardly from the center of the intermediate wall 147 for receiving the screw 133. The elastic member 131 is preferably an elastomer. In a preferred construction, the elastomer is made of neoprene or synthetic rubber, although other types of elastomeric materials may be used. The elastomer is machined to be received in inner component 129 around boss 151. In the preferred construction, the resilient member 131 has a base portion 132 with an aperture 138 and a pair of arm portions 142. However, other shapes may be used. In addition, other types of resilient materials may be used, such as either Bellville springs or coil springs.

The lock is assembled by placing the resilient member 131 around the projection 151 in the inner part 129. The combined inner part and resilient member may then be inserted laterally into the side of cavity 134 in outer part 127, i.e. with side edges 150. Once the projection 151 is aligned with the aperture 136, the screw 133 is preferably rotated into the projection 151 until it is received in the aperture 136. The screw ensures that the assembly is not accidentally scattered.

In use, after the adapter 34 is placed on the base 32, the lock 36 is inserted into the opening 110 with the tongue 57 received in the slot 103 (fig. 1). The screw 133 includes a head 153 with some provision for engaging a tool (not shown) for rotating the screw 153. In the preferred embodiment, screw head 153 has an inner flat 155 for receiving a suitable wrench. The free end of the screw 133 includes a bearing surface 157, and as the screw is advanced, the bearing surface 157 abuts the rear bearing surface 60.

Further advancing the screw 133 against the rear bearing surface 60 causes the rear surface 125 of the base wall 135 to push the rear wall 115 of the opening 110 rearwardly. This extension of the lock results in abutment 105 on adapter 34 being in close abutting relationship with front bearing surface 68 of base 32. Further advancement of the screw 133 following such abutment will cause the inner part 129 to move towards the outer part 127 to compress the resilient member 131 until the side wall 149 abuts the base wall 135. The side walls will abut against base wall 135 to prevent the resilient member from being over-compressed. If the elastomer is a non-compressible rubber material or the like, there is sufficient open space between the inner and outer parts to allow the inner part 129 to be pulled against the outer part 127. Depending on the resistance in coupling the adapter to the base, the resilient member may in some cases be compressed before the adapter is fully secured to the base. In any event, lock 36 first becomes a rigid locking member by bringing inner part 129 into abutting contact with outer part 127. As wear begins to develop between the adapter 34 and the base 32, the resilient member 131 expands to dampen movement of the adapter relative to the base and maintain the tooth assembly in a secure relationship. This expansion of lock 36 continues to hold the assembly tightly together until resilient member 131 reaches its maximum expanded state (i.e., when the inner component abuts lips 141, 143).

The bearing surface 157 on the screw 133 preferably has a concave arcuate surface for mating with the corresponding rear bearing surface 60 (fig. 4). In the most preferred construction, bearing surfaces 60 and 157 are each formed as a spherical portion. In this manner, as the adapter 34 deflects under lateral loads (i.e., as the adapter rotates about its center of rotation), the bearing surface 157 remains substantially in full contact with the rear bearing surface 60. Although the bearing surfaces 60 and 157 may be made to have the same radius of curvature, the bearing surface 157 on the screw 133 may be made to have a smaller radius of curvature so as to come into contact with the rear bearing surface 60 by circular contact. The spherical configuration of the rear base surface also enables the screw 133 to make rounded contact to maintain substantially full contact with the base 32 during any shifting of the adapter.

Alternatively, other locks may be used so long as they abut adapter 34 and base 32 to prevent the adapter from sliding forward off the base. For example, a lock with other adjustment means may be used, such as the fluid actuator disclosed in U.S. patent No.5653048 to Jones et al, which is hereby incorporated by reference. Similarly, openings and locks such as those disclosed in U.S. patent No.5088214 to Jones et al, which is hereby incorporated by reference, may also be used without an adjustment device.

In an alternative configuration, the weld adapter 175 may be mounted on the positioning structure 65 on the dredge cutterhead arms 48 without the base 32 (FIG. 19). While the use of such adapters does not provide the aforementioned ease of removal and installation of the mechanically attached adapters, the locating features still provide ease of locating and additional support for the adapters. In a preferred construction, adapter 175 includes a pair of bifurcated legs 177, 178 that straddle the arm, although a single leg (not shown) could be used. If a single leg is used, the leg will preferably be located on the upper side of the arm to facilitate welding of the adapter to the arm. The adapter includes a coupling structure 180 to matingly fit with the locating structure 65 to properly locate the adapter and, thus, the point (not shown) to maximize digging efficiency. As with base 32, adapter 175 includes a slot 183, and this slot 183 matingly receives projection 70, while the surfaces opposite side 79 and end 80 properly position and support the adapter in use. The adapter is then welded along all or part of its perimeter. Also, as with the projections 32, the adapter is preferably spaced from the grooved surface 72 to facilitate removal of the adapter from the arm.

In another alternative construction, the adapter 175a includes a coupling structure 180a for positioning and support, the coupling structure 180a not being located above the protrusion 70 (fig. 20). In this arrangement, each locating formation includes a pair of spaced surfaces having a particular shape and spaced to engage, support and properly locate a wear member. For example, the grooved surfaces 72 on each side of the projection 70 are formed with a shape that matches the inner edge surfaces of the bridge portions 185a of the connecting leg portions 177a, 178 a. The bridging surface 185a then rests against the grooved surface to properly position the teeth. An adapter with coupling structure 180a may include a larger slot 183a that does not engage protrusion 70, or may be used with an arm that does not include protrusion 70.

In another alternative configuration, another weld adapter may be mounted on base 32. In this configuration, the adapter includes a socket that matingly receives body 40 and includes a structure, such as a groove, that enables the arm to fit over, but not be connected to, a tongue on base 32. Alternatively, a base without legs or with a leg without a coupling tongue may be used with the welding adapter. In either case, the body 40 of the base 32 properly positions the adapter and provides support thereto, with the adapter then being welded to the arm.

The foregoing relates to preferred embodiments of the present invention. Various other embodiments exist and various changes and substitutions may be made without departing from the spirit and broader aspects of the invention.

Claims (35)

1. An apparatus for mounting a wear member on excavating equipment comprising:

a base adapted to be secured to a digging portion of an excavator, the base including a convex front bearing surface curved about two perpendicular axes and a rear facing bearing surface;

a wear member comprising: a concave abutment surface curved in both horizontal and vertical directions to abut the front bearing surface; an opening having a load-bearing wall; and a working portion projecting forward; and

a lock received in the opening to oppose the rear facing bearing surface and the bearing wall of the opening to prevent the wear member from loosening.

2. An apparatus as defined in claim 1, wherein the front bearing surface and the abutment surface each define a spherical portion.

3. A device as claimed in claim 1 or 2, wherein the rear-facing bearing surface is convex and curved.

4. A device in accordance with claim 1 wherein the lock includes a contact surface that cooperates with the rear-facing bearing surface and defines a spherical portion with the rear-facing bearing surface.

5. An apparatus as defined in claim 3, wherein the radius of curvature for the front bearing surface and the radius of curvature for the rear facing bearing surface originate from the same point.

6. The apparatus of claim 1, wherein the base comprises one of a tongue or a slot and the wear member comprises the other of a tongue or a slot, wherein the slot receives the tongue to provide support to the wear member.

7. The device as claimed in claim 6, wherein the tongue and groove each have a T-shaped configuration.

8. A device as defined in claim 1, wherein the lock includes a first contact surface opposite the opening-bearing wall and a second contact surface opposite the rear-facing bearing surface, wherein the lock further includes an actuator that selectively moves the first and second contact surfaces away from each other to tighten the fit of the wear member on the base.

9. A device according to claim 8, wherein the actuator comprises a screw, a free end of which defines one of the first and second contact surfaces.

10. A device as claimed in claim 9, wherein the free end of the screw defines the second contact surface.

11. An apparatus as defined in claim 8, wherein the lock includes a resilient member, wherein the actuator compresses the resilient member and the resilient member expands the lock to secure the wear member in engagement with the base.

12. A device as claimed in claim 11, wherein the resilient member is an elastomer.

13. A device in accordance with claim 11 wherein said lock further comprises at least one stop for limiting the degree of compression of said resilient member.

14. The apparatus of claim 1 wherein said base is cast as an integral part of an arm on a dredge cutterhead.

15. A wear member for attachment to an excavator to which a base is secured, the wear member comprising: an opening for receiving a lock; a working portion projecting forward; and a rearwardly facing abutment surface adapted to abut the bearing surface of the base and defining a concave portion that curves in both the horizontal and vertical directions.

16. A wear member in accordance with claim 15 wherein the abutment surface defines a spherical portion.

17. A wear member in accordance with claim 15 or 16 wherein the opening has a rear wall with a curved configuration.

18. A wear member in accordance with claim 17 in which the wear member is an adapter for mounting a tooth point.

19. A wear member in accordance with claim 15 including a leg defining one of a tongue or a slot for mating with another of the tongue and the slot formed in the base.

20. A wear member in accordance with claim 15 in which the wear member is an adapter for mounting a tooth point.

21. A wear member for attachment to an excavator to which a base is secured, the wear member comprising: a rear mounting portion, a front working portion, a rearwardly facing abutment surface adapted to abut the load bearing surface of the base, the abutment surface being concave and curved in both a horizontal and vertical direction, and an opening for receiving a lock, the opening having a front wall portion and a rear wall portion, the rear wall portion being adapted to oppose the lock to secure the wear member to an excavator, the rear wall portion being concave and curved.

22. A wear member in accordance with claim 21 wherein the curvature of the rear wall portion is defined by a first radius of curvature and the curvature of the abutment surface is defined by a second radius of curvature, wherein the first and second radii of curvature both originate from the same location.

23. A wear member in accordance with claim 21 or 22 wherein the abutment surface and the rear wall portion each define a spherical portion.

24. A base for attaching a wear member to excavating equipment, the base comprising a forwardly facing convex bearing surface curved in two perpendicular directions for abutment with complementary abutment surfaces on the wear member, and a rear mounting component adapted to be secured to the excavating equipment.

25. A base according to claim 24, including a rearwardly facing bearing surface for abutting the lock to retain the wear member on the base.

26. A base part as claimed in claim 24 or 25, wherein the forwardly facing convex bearing surface is curved across its entire surface.

27. The base of claim 24, wherein said forward-facing convex bearing surface is defined by a uniform, continuous curvature in either of two perpendicular directions.

28. The base of claim 24, wherein said forwardly facing convex bearing surface defines a spherical portion.

29. A base as claimed in claim 24, which includes flat surfaces extending rearwardly from top and bottom ends of said forwardly facing convex bearing surface.

30. A base according to claim 24, including a planar surface extending rearwardly from an opposite side of said forwardly facing convex bearing surface.

31. The base of claim 24, further comprising a tongue received in a slot formed in the wear member.

32. The base of claim 31, wherein said tongue includes a pair of opposed laterally extending shoulders.

33. A base adapted to be secured to an excavator having a digging edge for mounting a wear member, the base including a coupling structure for receiving and supporting a wear member; and a body having a convex front bearing surface curved about two perpendicular axes for abutting a complementary surface of the wear member and a rear facing bearing surface for abutting the lock.

34. The base of claim 33, wherein a first radius of curvature at least partially defines the convex front bearing surface and a second radius of curvature at least partially defines the rear facing bearing surface, wherein the first and second radii of curvature originate from a same point.

35. A base portion as claimed in claim 33 or 34, wherein the convex front bearing surface and the rear facing bearing surface each define a spherical portion.