Patent Grant
8720087
The present invention pertains to coupling assemblies for releasably securing separable parts together, and especially for securing together components of a wear assembly for excavating equipment and the like. The general field of this invention may be the same as or similar to those described, for example, in U.S. Pat. Nos. 7,174,661 and 7,730,652 owned by BSCO Corporation of Portland, Oreg. These earlier ESCO patents are incorporated herein by reference in their entirety.
Excavating equipment typically includes various wear parts to protect underlying products from premature wear. The wear part may simply function as a protector (e.g., a wear cap) or may have additional functions (e.g., an excavating tooth, which functions to break up the ground ahead of the bucket as well as protecting the underlying digging edge). In either case, it is desirable for the wear part to be securely held to the excavating equipment to prevent loss during use, and yet be capable of being removed and replaced when worn. In order to minimize equipment downtime, it is desirable for the worn wear part to be capable of being easily and quickly replaced in the field. Wear parts are usually formed of three (or more) components in an effort to minimize the amount of material that must be replaced on account of wearing. As a result, the wear part generally includes a support structure that is fixed to the excavating equipment, a wear member that mounts to the support structure, and a lock to hold the wear member to the support structure.
As one example, an excavating tooth includes an adapter as the support structure, a tooth point or tip as the wear member, and a lock or retainer to hold the point to the adapter. The adapter is fixed to the front digging edge of an excavating bucket and includes a nose that projects forward to define a mount for the point. The adapter may be a single unitary member or may be composed of a plurality of components assembled together. The point includes a front digging end and a rearwardly opening socket that receives the adapter nose. The lock is inserted into the assembly to releasably hold the point to the adapter.
The lock for an excavating tooth is typically an elongate pin member that is fit into an opening defined cooperatively by both the adapter and the point. The opening may be defined along the side of the adapter nose, as in U.S. Pat. No. 5,469,648, or through the nose, as in U.S. Pat. No. 5,068,986. In either case, the lock is inserted and removed by the use of a hammer. Such hammering of the lock can be an arduous task and impose a risk of harm to the operator.
The lock is usually tightly received in the passage in an effort to prevent ejection of the lock and the concomitant loss of the point during use. The tight fit may be effected by partially unaligned holes in the point and adapter that define the opening for the lock, the inclusion of a rubber member in the opening or in the pin, and/or close dimensioning between the lock and the opening. However, as can be appreciated, an increase in the tightness in which the lock is received in the opening exacerbates the difficulty and risk attendant with hammering the locks into and out of the assemblies.
The lock additionally often lacks the ability to provide substantial tightening of the point onto the adapter. While rubber members have been provided in prior locking systems to provide some tightening of the wear member on the support structure, it has tended to provide only limited benefit as the rubber lacks the strength needed to ensure a tight fit when the teeth are under load during use. Most locks also fail to provide any ability to be retightened as the parts become worn. As a result, many locks used in teeth are susceptible to being lost as the parts wear and the tightness decreases. Prior locks that provide take up or the ability to be retightened tend to rely upon threads or wedges, which commonly suffer from removal difficulties and/or safety issues.
Shortcomings in the locking arrangements are not limited strictly to the mounting of points on adapters. In another example, an adapter is a wear member that is fit onto a lip of an excavating bucket, which defines the support structure for the adapter. While the point experiences the most wear in the system, the adapter will also wear and in time need to be replaced. It is common for adapters to be mechanically attached to a bucket lip so as to permit the use of harder steel and to accommodate replacement in the field. One common approach is to use a Whisler style adapter, such as disclosed in U.S. Pat. No. 3,121,289 (see FIG. 8). In a traditional Whisler system, the adapter is formed with bifurcated legs that straddle the bucket lip. The adapter legs and the bucket lip are formed with openings that are aligned for receiving the lock. The lock in this environment comprises a generally C-shaped spool and a wedge. The arms of the spool overlie ramps on the rear end of the adapter legs. The ramps on the legs and the inner surfaces of the arms are each inclined rearward and away from the lip. The wedge is then hammered into the aligned openings to force the spool rearward. This rearward movement of the spool causes the arms to tightly pinch the adapter legs against the lip to prevent movement or release of the adapter during use.
However, the hammering of the wedge into and out of the openings in a Whisler-style lock tends to be difficult and potentially hazardous. Removal can be particularly difficult as the bucket must generally be turned up to provide access for driving the wedges out of the assembly. In this orientation of the bucket the worker must access the opening from beneath the bucket and drive the wedge upward with a large hammer. The risk is particularly evident in connection with large buckets. Also, because wedges can eject during service, it is common for the wedges to be tack-welded to its accompanying spool, which eliminates any retightening and makes wedge removal more difficult.
In many assemblies, other factors can further increase the difficulty of removing and inserting the lock when replacement of the wear member is needed. For example, the closeness of adjacent components, such as in laterally inserted locks (see, e.g., U.S. Pat. No. 4,326,348), can create difficulties in hammering the lock into and out of the assembly. Fines can also become impacted in the openings receiving the locks making access to and removal of the locks difficult.
There have been some efforts to produce non-hammered locks for use in excavating equipment. For instance, U.S. Pat. Nos. 5,784,813 and 5,868,518 disclose screw driven wedge-type locks for securing points to adapters, and U.S. Pat. Nos. 4,433,496 and 5,964,547 disclose screw-driven wedges for securing adapters to buckets. While these devices eliminate the need for hammering, they each require a number of parts, thus, increasing the complexity and cost of the locks. The ingress of fines can also make removal difficult as the fines increase friction and interfere with the threaded connections. Moreover, with the use of standard threads, the fines can build up and become “cemented” around the threads to make turning of the bolt and release of the parts extremely difficult as can corrosion and damage to the threads.
U.S. Pat. Nos. 6,986,216, 7,174,661 and 7,730,652 disclose locking arrangements for wear assemblies that rely upon a threaded wedge that engages a thread formation on the spool or wear member, and is rotated to drive the wedge into and out of the opening. These systems require minimal components, eliminate hammering, and alleviate the removal problems associated with prior systems. However, they lack the ability to provide substantial take up to ensure a tight fit with the lip or other supporting structure, or effective retightening after wear occurs.
Typically, in a mining operation, a major earthmoving machine like a large cable shovel or dragline machine may have as many as three buckets dedicated to the machine. These buckets will include one bucket that is actively in use on the machine, one bucket that has been taken off the machine and is in the rebuild shop (e.g., to have various wear members removed and replaced with new wear members and to rebuild the lip for the tooth base and shroud fit areas), and one “ready line” bucket. The ready line bucket is a bucket that is new or has been through the re-build process and is ready to go back to work. The ready line bucket is needed because a bucket rebuild can take months to complete. It can be used on a scheduled maintenance cycle or, as can happen, when a major failure occurs with the bucket on the machine. Because the rebuild process takes so long, a mine cannot afford to not have a bucket available to put on a machine in case of emergency. The downtime and associated economic loss would be too great.
While larger mining operations (e.g., operations involving multiple cable shovels and/or dragline machines) may not have three buckets dedicated to each machine, the operation will still typically have a sufficient number of ready line buckets available, if needed, to prevent excessive downtime (i.e., to avoid having a machine inoperable while waiting for a bucket rebuild job to be completed). The need for numerous ready line buckets represents a significant cost for the mining operation.
Because the lip rebuild tends to be the most time consuming part of the bucket rebuild process, reducing the number of rebuilds by lengthening the time between rebuilds would be a huge savings. Such a reduction in the number or frequency of rebuilds to the lip or other parts of the bucket would save the end user the money and time needed to perform these rebuilds as well as avoid the downtime associated with having the excavating bucket detached from the machine or unavailable for use in moving material. Reducing the number of lip rebuilds could constitute a huge savings in terms of less inventory of replacement buckets, fewer welders required to do these rebuilds, and a more forgiving system that is easier to operate and can be changed when it is more convenient for the operation.
Since the bucket lip takes substantial abuse and is under considerable load during use, it needs to retain its strength and integrity to avoid failure. While welding on a lip rebuilds the leading edge of the lip to its original form, it also poses a risk to the lip if not done correctly. The lip must be preheated and welding procedures must be followed very carefully in order to avoid developing cracks. A cracked lip will necessitate the bucket being removed from the machine and repaired. However, if one does not need to weld repair the lip as often, then one possible failure mode is reduced or limited, thus minimizing the chances for a lip crack or failure.
One factor that may influence the need to repair or rebuild the lip on a bucket relates to whether the system for coupling the wear member to the lip is capable of securely engaging the parts together. The coupling system must be able to move the wear member a sufficient distance with respect to the lip to seat the wear member onto the lip. This amount of movement is referred to as “take up” (e.g., the coupling system must move the wear member a sufficient distance with respect to the lip to “take up” any gap or distance between the wear member and the lip). If a coupling system can only move a wear member a small distance with respect to the lip, the coupling system has a small take up capability, and in such systems, the mine operator may be forced to rebuild the lips more frequently (to assure that the coupling system will have sufficient take up to move the wear member and securely hold it against the lip). For coupling systems with a small amount of available take up, the lip rebuild also must be relatively precise to assure that the coupling system will be able to move the wear member and hold it onto the lip. Systems with wear members that are not tightly held to the supporting structure will tend to suffer more wear and tend to be more susceptible to wear member loss. While premature wearing of the lip may be of primary concern, premature wearing of other support structures, such as adapters, can also increase downtime and costs due to more frequent replacement.
Accordingly, improvements in releasable coupling systems for securing wear members to the digging edge of a bucket would be welcome in the mining and construction industries. There remains a need for coupling systems that are easy and safe to install and remove, are reliable in use, enable substantial take up, allow longer time periods between bucket rebuilds, permit a wider range of dimensional variation in the manufacturing processes for the various parts, and lead to less machine downtime. Such improvements would result in reduced costs by decreasing the need for ready line buckets and the expense associated with rebuilding the digging edge of the buckets.
This invention relates to improved assemblies in which separable parts are releasably held together in a secure, easy, and reliable manner. The present invention is particularly useful for securing wear members to support structures in conjunction with excavating equipment and excavating operations. Coupling assemblies of the present invention are easy to use, are reusable, are securely held in the wear assembly, and operate to effectively tighten the wear member onto the support structure.
One aspect of the invention pertains to a lock for use in securing a wear member to a support structure that includes a wedge and a spool wherein the spool pivots or rotates about a fulcrum on the support structure to tighten and securely hold the wear member to the support structure as the wedge is driven into the assembly. The pivoting of the spool, as opposed to the rearward translation of spools in the prior art, provides increased take up to ensure a tight fit even after considerable wear of the underlying support structure. The invention permits effective retightening of the wear member and allows the use of larger manufacturing tolerances between engaged parts. The increased take up allows the lip leading edge, as well as all other components, to have a longer life before it needs to be rebuilt, which can lead to lower costs on account of reduced bucket inventory, labor costs, and/or equipment downtime associated economic loss. Moreover, the improved take up is preferably accomplished in a hammerless lock for enhanced safety.
Additional aspects of this invention relate to coupling assemblies in which a large amount of take up is available in relatively compact and internally contained locks (i.e., the locks may be completely or substantially internally contained within openings provided in the components to be coupled together). The large amount of available take up also aids in the assembly and disassembly of the coupling because the various parts can be relatively loosely fit together until tightening is completed and can be made relatively loose when the wedge is loosened (so that disassembly is easy and quick). Additionally, the compactness of the locks allows the majority or all of the lock to be contained within openings provided in the wear member and/or the support structure, thereby protecting the lock and its parts from material flow (e.g., protecting the spool and wedge against damage due to contact with rocks or other materials during use).
In one embodiment of the invention, a lock for securing a wear member to a support structure includes a wedge and a spool. The spool is formed with an axially convex engagement surface in which to engage the wedge. This convex engagement surface causes the spool to pivot or rotate about a fulcrum on the support structure for enhanced take up.
In another aspect of the invention, a lock for securing a wear member to a support structure includes a wedge, a spool and an insert that all move relative to each other to effect pivoting or rotation of the spool about a fulcrum on the support structure for increased take up. The use of a movable insert increases the amount take up, in some cases, up to three to four times what is available in prior wedge and spool systems.
In one embodiment of the invention, the insert is movably secured to the spool to engage the wedge. As the wedge is driven into and out of the assembly, the engagement of the insert with both the wedge and the spool causes the spool to rotate to tighten the fit of the wear member on the support structure.
In another embodiment of the invention, the insert and the spool engage the wedge on opposite sides and are secured to the support structure such that the insert and spool each pivot or rotate as the wedge is driven into and out the assembly.
Another aspect of this invention relates to coupling assemblies that provide elastic tightening between the wedge and the insert. This feature helps maintain secure contact between the insert and the wedge during use, secures the insert to the spool without the wedge (such as during shipping, installation and removal), and provides a limited tightening benefit by way of elastic take up.
In another aspect of the invention, a part of the wear member overlies the support structure and includes a hole. The hole has a first portion that extends entirely through the overlying part in a first direction for receipt of a wedge and spool locking assembly, and a second portion laterally outside of the first portion that extends only partially through the overlying part on account of the presence of a ledge. A bearing portion of the spool extends over the ledge to prevent movement of the wear member away from the support structure, to hold the spool in place without the wedge in the hole, and to apply no forces to urge the spool in directions transverse to the first direction during use.
In one embodiment of the invention, the ledge extends entirely across a rear end of the hole. In another embodiment, the ledge is provided only laterally of the first portion of the hole. In either case, the second portion preferably includes a rear wall against which the spool pushes to tighten the wear member on the support structure. The second portion of the hole also preferably includes a front wall to retain the spool in a rearward end of the first portion of the hole for easy insertion of the wedge.
Other aspects, advantages, and features of the invention will be described in more detail below and will be recognizable from the following detailed description of example structures in accordance with this invention.
The present invention is illustrated by way of example and not limited in the accompanying figures, in which like reference numerals indicate the same or similar elements throughout, and in which:
The reader is advised that the various parts shown in these drawings are not necessarily drawn to scale.
The following description and the accompanying figures disclose example features of coupling assemblies for releasably holding separable parts together in accordance with examples of the present invention. While the invention has broader applications, it is particularly useful in releasably securing wear members to support structures in excavating equipment and excavating operations. The wear members may be, for example, points, adapters, shrouds, or other replaceable components. Examples of machinery on which locking mechanisms in accordance with this invention may be used include, but are not limited to, shovel dippers, dragline buckets, front end loaders, hydraulic shovels, dredge cutters, and LHD buckets.
As shown in
The shroud opening 110 preferably includes a narrower first portion 110a and a wider second portion 110b. As illustrated, the first portion 110a of the opening 110 defines the front of the opening and extends completely through upper leg 108a of the shroud 106, whereas the rear portion 110b extends only partially through the upper leg 108a. In one embodiment, ledge 112a extends across the entire width of wider rear portion 110b. In another embodiment (not shown), ledge 112a may only be provided in side portions 110c with the remainder of the hole being the first portion extending all the way through the leg. In either embodiment, ledge 112a extends into the opening 110 and provides a surface over which a portion of the lock extends to help prevent the shroud 106 from pulling upward and away from the lip when put under certain loads during digging. In the present invention, the lower leg 108b is preferably shortened to reduce the material needed to make the part, the cost of manufacture, and the weight of the wear member on the machine.
A lock 150 in accordance with the invention includes a threaded wedge 350 such as disclosed in U.S. Pat. No. 7,174,661, and a spool 200. The spool and wedge cooperate with each other, and with the wear member and the support structure, so that the spool rotates as the wedge is driven into the assembly to provide substantial take up to pull the wear member tight against the support structure. While a threaded wedge and spool are preferred to avoid the use of a hammer, a hammered wedge and spool could be used in the invention.
In the embodiment illustrated in
As seen in
Upper bearing portion 202 includes laterally extending side portions 209. Side portions 209 extend laterally outward of the stem portion 201 of the spool 200 and laterally outward of the narrower portion 110a of opening 110 for receipt into side portions 110c of the wider rear portion 110b of the opening 110. These laterally extending side portions 209 are preferably confined by rear wall 112, ledge 112a and a front wall 110d to hold the spool in place prior to insertion of the wedge during installation, and after removal of the wedge during replacement of the wear member. More specifically, the engagement of the side portions 209 with ledge 112c and front wall 110d prevent the wedge from slipping through the hole 152 in lip 102 to ease installation. This not only makes installation easier and quicker, it can be a considerable advantage when installation occurs at night or during inclement weather. Finding a spool that has dropped through the lip can be difficult, and it can also put a worker in a hazardous position under the bucket. These same advantages are also provided during removal, i.e., side portions 209 retain spool 200 to the shroud 106 after the wedge as been taken out of the assembly. The front wall 110d holds the spool in a rearward position to provide a preset space to receive the leading end of the wedge during installation. Other configurations besides side portions 209 could be provided to achieve the same purpose, but this construction is preferred as it is an efficient structure relative to the overall construction, it does not impair the strength or operation of the shroud or other components of the wear assembly, it is reliable, and it is cost effective to manufacture. Further, as noted above, ledge 112c could be confined solely to side portions 110c such that only side portions 209 perform the functions of pushing on rear wall 112 and/or preventing movement of leg 108a away from the lip 102.
Rear side 200a of the spool 200 further includes a second or lower bearing portion 204 that engages corner 156d in the opening 152 of the lip 102. The connection of bearing portion 204 to stem portion 201 may include a rounded corner in similar size and shape to the rounded corner edge 156d of the lip wall 156. In this example structure, the spool 200 generally forms a C-shaped arrangement that fits into the openings 110 and 152 of the shroud 106 and lip 102. Corner 156d defines a fulcrum 157 for the spool to facilitate pivoting or rotation of the spool for increased take up. As noted above, other constructions could be used as the anchor for the spool.
In a preferred construction, lock 150 also includes an insert 250 that is movably secured to the spool. The insert defines the connection between the wedge and the spool in such a way that the spool pivots or rotates about fulcrum 157 as the wedge is driven into and out of the assembly so as to provide the wear member with substantial take up.
The opposite front side 200b of the spool 200 includes the hollowed out portion or recess 210 into which the insert 250 is received. The recess 210 in this example is defined by (a) a generally arched inner surface 210a, (b) two opposing side walls 210b and 210c, and (c) a generally open space 210d between the side walls 210b and 210c opposite the inner surface 210a. Smoothly rounded edges and corners are preferably provided between the various surfaces and walls of the recess. Inner surface 210a is preferably arcuate in shape along the length of stem 201 (i.e., in a vertical direction as shown in
The side walls 210b and 210c of recess 210 are provided to hold the insert to the spool 200 and, in cooperation with inner surface 210a, guide the insert along its prescribed path of movement relative to the spool. In one embodiment, side walls 210b, 210c extend somewhat inward toward one another as they extend forward and away from the inner surface 210a. For example, the side walls may converge at an angle within a range of 15° to 45°, and in one preferred example at an angle of about 30°, though other tapers are possible. This forward tapering of the side walls results in a front space 210d that is narrower than the width of the insert at its widest point to prevent loss of the insert through the front of the recess. The side walls 210b and 210c also preferably taper inward toward one another in a direction from a top end 214 to a bottom end 216 of the spool 200. For example, the side walls may taper along the length of stem 201 within a range of 2° to 15°, and preferably at an angle of about 7°. Preferably, this taper of the side walls should be roughly equal to the taper of the wedge simply for ease of use and space requirements but is not required to be, though other tapers are possible. This downward tapering results in side walls 210b, 210c defining a space that is narrower than the width of the insert 250 at its wider top end to prevent loss of the insert out the bottom of recess 210. These various tapers define a path to guide the insert 250 along its desired course without binding and without loss of the insert from the spool 200. The tapers also function to retain the insert in the spool when the wedge is not engaged, such as during shipping, installation and removal of the lock. The top end of recess 210 is open and sufficiently large to define an inlet 210e through which the insert is fit into the recess. While the insert is preferably slid into recess 210 during initial manufacture of the lock, it could be inserted by the end user prior to installation into the wear assembly. Other arrangements (i.e., beside the tapering side walls) could be used including, for example, the use of a key and keyway, rim portions on the outer edges of the walls defining the hollowed out portion to overlie the insert to retain and guide the insert as desired.
As noted above, the insert 250 is capable of moving within recess 210 (i.e., relative to the spool 200) in response to downward movement of the wedge. The recess forms a guide for directing the insert along a prescribed path. As the wedge is driven into the assembly to tighten the connection, the spool is rotated or pivoted about fulcrum 157 such that upper bearing portion 202 pushes against rear wall 112 to push the shroud 106 rearwardly and tightly against the lip 102, i.e., so that bearing surface 104a on the shroud is tightly abutted against the front end 151 of lip 102.
Recess 210 preferably includes a cavity 212, which as illustrated is an elongate vertical slot in inner surface 210a, to provide a space for receiving and mounting a resilient member 302 (
Insert 250 is received within recess 210 of the spool 200 in this example coupling assembly (
The front surface 256 of the insert 250 may be tapered from its top end 260 to its bottom end 262 as shown in
The tapering of the sidewalls 258a and 258b of insert 250 from back to front and the complementary tapering of the sidewalls 210b and 210c of recess 210 from back to front function to prevent loss of insert 250 through the open space 210d in recess 210. As best seen in
The wedges 350 of these illustrated examples further include threads 364 regularly spaced along the longitudinal length L of the wedge 350. These threads 364 are sized and spaced so as to engage with the thread segments 254 of the insert 250, as illustrated in
The assembly and operation of one example of a wear assembly 400, including the example parts shown and described above in conjunction with
The upper end 261 of the front side 200b of spool 200 (i.e., between inlet 210e and the top end 214 of spool 200) is preferably formed as a trough 263 for clearance to receive that portion of the wedge 350 that has not been driven downward into engagement with insert 250. Because of the pivoting of spool 200 during installation and removal, the trough 263 preferably deepens as it extends away from inlet 210e to provide ample clearance to receive the wedge during initial installation (i.e., with the spool at its most forward orientation).
Next, the shroud 106 is fit over and around the front end 151 of the lip 102 as generally shown in
At this time, the wedge 350 is inserted through opening 110 and into opening 152 along the front wall 154 of the opening 152 (as generally shown by arrow 408 in
The wedge 350 may be turned and tightened to the extent necessary to firmly place the bearing surface 104a at the front end of the gap 104 between the legs 108a, 108b of the shroud 106 against the front end 151 of the lip 102. Tightening of the wedge 350 will first move the shroud 106 against the lip 102 to take up the gap between the parts. Further tightening will displace the resilient insert 302 in the hollowed out portion 210. The positioning shown in
As the wedge 350 is driven into the wear assembly 400, the insert 250 is moved rearward by the downward movement of the wedge. This rearward movement of insert 250 causes the spool 200 to pivot or rotate rearwardly (i.e., clockwise as shown in the drawings) about fulcrum 157; i.e., lower bearing portion 204 of spool 200 remains engaged with mounting corner 156c defining the fulcrum for spool 200. Upper bearing portion 202 rotates rearwardly to press against rear wall 112 and push shroud 106 farther onto lip 102. This rotation of the spool causes the insert to translate along inner surface 210a. The insert 250, though, remains engaged with the wedge 350. Neither the wedge nor the insert rotate relative to the lip. While the insert will tend to be driven rearward, the insert 250 may not move much vertically relative to the lip 102 as the wedge is driven into the assembly.
This rotation of spool 200, caused by the interaction of wedge 350 with insert 250, results in considerably greater take up as compared to traditional Whisler arrangements or other non-traditional wedge and spool locks such as disclosed in U.S. Pat. No. 7,730,652. Although, as a practical matter, the actual rearward movement of a traditional spool may be made up of a series of irregular shifting motions (i.e., where one arm may move at times without the other), the overall movement of the traditional spool over time is to translate directly rearward. In the past, the spool was to have this linear rearward translation irrespective of whether the spool arms rode up ramps to pinch the wear member legs against the lip (such as shown in U.S. Pat. Nos. 7,730,652, 7,174,661 (FIG. 12), and U.S. Pat. No. 3,121,289) or simply laid over the wear member portions and exerted a rearward pushing force (such as shown in U.S. Pat. No. 7,174,661 (FIG. 8)). The take up provided by wedge and spool locks of the prior art was limited solely to the outward taper of the wedge. On account of balancing the force needed to install the wedge and lessening the risk of wedge ejection, the taper on such wedges has been modest, which, in turn, limits the available take up for the wear member. This novel use of the insert and pivoting of the spool results in a take up which is in some cases three to four times more than in prior wedge and spool locks without any increase in the taper of the wedge.
Reference is made to
The rotation of spool 200 about fulcrum 157 may result in an upward swinging of upper bearing portion 202 so as to form a slight gap between it and ledge 112a (if a gap didn't exist already). Whether a gap will be created depends on the relative angle of the spool with respect to the shroud. However, since the upper bearing portion 202 preferably does not normally pinch upper leg 108a against the lip, such a gap does not hinder the mounting of the shroud on the lip. Even in the rotated position, with the bearing surface 104a tightly against the front end 151 of lip 102, the upper bearing portion 202 still prevents upper leg 108a from having any undue movement away from the lip during digging.
Over the course of time and use (e.g., under the harsh conditions to which equipment of this type may be exposed during excavation), the front end 151 of the lip 102 will generally become worn and the fit of the wear member will loosen. As wearing occurs, the resilient insert 302 will at first push outward on the insert 250 to provide limited resistance to movement of the wear member under load. However, as wear continues and the gap between the shroud 106 and the lip 102 widens, even more movement will result, which may cause unwanted rattling and the like between the lip 102 and the shroud 106. Loose mounting of wear parts tends to increase wearing, and if it gets to be too great, increases the risk of wedge ejection. Accordingly, over time, a user may wish to retighten the coupling between the shroud 106 and the lip 102. Alternatively, the shroud may be designed to wear out at about the time retightening is needed so that the greater tightening of the wedge occurs at the time a new shroud is mounted on the lip. This retightening or further tightening can be accomplished by rotating the wedge 350 (as shown in
As additional use takes place, the front end 150 of the lip 102 may become further worn. This wear may again cause the coupling to become loose, which again may cause rattling, undesired movement between the lip 102 and the shroud 106, etc. Accordingly, the user may again wish to retighten the lock 150 between the lip 102 and the shroud 106 or initially tighten a new wear member onto a further worn lip. This can be accomplished by again rotating the wedge 350 (as shown in
Notably, the arrangement described above in conjunction with
As described above, the resilient member 302 applies a force that urges the insert 250 away from the inner surface 210 of the spool 200, which increases the engagement of the threads between the insert 250 and the wedge 350. The effect of this force is to push the spool 200 away from the wedge 350, and because the spool 200 is in direct contact with the wear member, it maintains some pressure on the wear member in an effort to tighten the fit of the shroud on the lip. In one example, the resilient member 302 provides about 4000 pounds of force in its most compressed condition, which as noted above is applied to hold the wear member against a lip. Thus, as the forces on the locking mechanism vary over the course of use (e.g., due to dynamic loading and impacts), the resilient member 302 helps maintain a tighter connection between the coupled parts, to reduce in a limited way deterioration of the parts caused by impact loading (and thus reduces the need or frequency at which the part(s) must be rebuilt). This feature is referred to herein as “elastic take up.” The resilient member 302 also helps prevent undesired wedge rotation during use by holding the insert 250 and the wedge 350 in tight, friction force contact (particularly for polygonal cross section wedges, but also, to at least some degree, for round cross section wedges).
Notably, in this wear assembly 400, the various components are coupled together without a vertical clamping force (i.e., the spool 200 does not vertically clamp the shroud 106 to the lip 102 or apply a clamping force between surfaces 156c and 112a) under normal use. The lack of a vertical clamping force between the lip 102 and the shroud 106 substantially reduces the stresses on the spool 200 and makes the coupling and relative movement of the parts simpler and easier. An expansive, spreading force on bearing portions 202, 204 is applied only when a sufficiently large downward force is applied on front end 118 of shroud 106 such that upper bearing portion 202 functions to hold upper leg 108a to the lip 102.
In addition to the improved “take up” features described above, the rotating insert 250 that fits into the spool 200 may provide additional benefits. For example, the use of rotatable insert 250 provides for better alignment between the threads associated with the spool (i.e., those on the insert) with those on the wedge 350 than would otherwise be possible. The use of rotatable insert 250 also helps provide a smoother and more uniform loading between the spool 200 and the wedge 350. In other wedge and spool systems, the wedge and spool may not be well aligned (i.e., one component may be cocked slightly relative to the other), which can result in the presence of a pinch point somewhere along their interface, which produces a stress concentration point. This stress concentration point could be located anywhere along the path of engagement, e.g., near the bottom of the wedge/spool interface if the wedge has slightly too shallow of taper, near the top if the wedge has too wide a taper, somewhere in the middle if the spool is slightly out of tolerance, etc. Nonetheless, there will be some higher stressed point along the line of contact between the spool and the wedge. Locking mechanisms in accordance with the present invention, however, with the rotating insert 250, tend to automatically adjust to move away from a higher stress to a lower stress condition and thus tend to equalize the loading over the insert's length with the wedge and also uniformly seating the insert into the spool to provide a more uniform load on the spool. The reductions in stress provided by rotation of the insert as well as having no normal pinching of the wear member against the lip, leads to a longer useful life for lock 150 such that the locks can often be reused for mounting multiple successive wear members before they need to be replaced.
Another advantageous feature of locks according to the invention relates to the ability of the lock to actually tighten within the assembly if the wedge 350 is forced upward from the bottom (e.g., in the direction of arrow 470 in
Many variations in the wear assembly 400 and the individual components thereof are possible without departing from this invention. As some more specific examples, the various components, such as the spool 200, the insert 250, the wedge 350, and the wear member 106 may take on a variety of different sizes, shapes, and constructions without departing from this invention. In some examples, the lock components of the wear assembly 400 may substantially or completely fit within the openings 110 and 152 of the parts to be coupled. Also, the various components of the coupling system may be made from any desired materials without departing from this invention, such as steels, and the components may be manufactured in any desired manner without departing from this invention, such as through casting, forging, fabrication, or machining techniques. The spool 200, wedge 350 and insert 250 may be made of any suitable or desired materials for their intended application and in any suitable or desired manner without departing from this invention. For excavating equipment, the lock components are preferably cast in low alloy steel for strength, hardness and toughness. As noted above, locks in accordance with the invention including a wedge, spool and insert (as described above) can be used to secure other wear members in place, such as a point to an adapter. In this construction, the adapter nose would include the hole with the fulcrum and the point the hole with the rear wall to be engaged by the spool for holding the point to the adapter. Further, while the lock is shown only in a vertical orientation (which is common when installing a lock to hold a wear member (such as a shroud) to the lip of a bucket), it could be inserted horizontally (e.g., parallel to the lip), particularly when securing a point to an adapter or other such member to a base. Of course, references to relative terms such as vertical and horizontal are for convenience with reference to the figures. Excavating equipment is capable of assuming various orientations other than what is shown.
Other spool variations can be used. For example, a lock in accordance with the present invention may operate without an insert. In this example, the spool 275 is provided with a threaded trough 276 in which to engage with a threaded wedge 350 (
As another alternative of the invention, the resilient member need not be separate from the insert. For example,
Another example coupling assembly is described below in conjunction with
When mounted in the lip 600, the pivoting insert 650 may be arranged such that its rounded exterior surface 658 extends within and is oriented proximate to the concave front wall 606 of the lip 600 and such that the concave bearing surface portion 652 faces rearward and is exposed within the opening 602 of the lip.
The front side 700b of spool 700, opposite the side 700a, includes thread segments 706 that engage with the threads 364 provided on the wedge 350. The thread segments 706 extend about ⅓ to ⅕ of a full circumference and are spaced apart along substantially the entire longitudinal length L of the spool 700. While any number of individual thread segments 706 may be provided along the longitudinal length L of the spool 700 (e.g., from 2 to 15), the illustrated example includes 7 thread segments 706. The thread segments 706 are integrally formed as part of the spool 700 structure, e.g., using any desired fabrication technique, such as casting.
Then, the shroud 106 is fit over the lip 600 with the pivoting insert 650 so that lip is received in the gap 104 of the shroud 106 defined between the legs 108a, 108b until bearing surface 104a contacts the front end 616 of the lip 600. This action is generally illustrated in
Once assembled to the extent described above, the wedge 350 is inserted into the opening 110 (shown generally in
At the point in time shown in
Over the course of time and use (e.g., under the harsh conditions to which equipment of this type may be exposed during excavation), the front end 616 of the lip 600 may become worn. This is shown in
The downward movement of the wedge 350 causes the insert 650 to rotate clockwise (from the perspective of
With additional use and wear over the course of time (e.g., under the harsh conditions to which equipment of this type may be exposed during excavation), the front end 616 of the lip 600 may become further worn. This is shown in FIG. 14E by the gap G that has again developed between the front end 616 and the interior surface of the opening 104 (the gap G being the result of material of the lip 600 and/or the shroud 106 ablating away). As stated before, this wearing action again may cause the coupling to become loose, which may cause rattling, undesired movement between the lip 600 and the shroud 106, accelerated wear, etc. Accordingly, the user again may wish to retighten the coupling between the lip 600 and the shroud 106 or mount a new shroud on the lip. As described above, this can be accomplished by further rotating the wedge 350 with respect to the remainder of the assembly 800 (as shown in
This further downward movement of the wedge 350 causes the insert 650 to further rotate clockwise (from the perspective of
Notably, from a comparison of
The arrangement described above in conjunction with
Insert 950 includes a hollowed out or concave bearing surface 952. This bearing surface 952 engages a wedge in the finally assembled lock. Each side 954a and 954b of insert 950 includes a resilient strip member 956a and 956b, respectively. The resilient strip members 956a and 956b may be made from blocks of elastomeric material, such as rubber and the like. These resilient strip members 956a and 956b help support the pivoting insert 950 when it is mounted in the opening 902 of the lip 900 by engaging the side walls 908a and 908b of the opening 902. The pivoting insert 950 includes a rounded surface 958 opposite the bearing surface portion 952. The rounded surface 958 may have curvature that generally matches the curvature of the opening 902 front surface 906.
When mounted in the opening 902 of the lip 900, insert 950 is arranged such that its rounded exterior surface 958 is proximate to the bowed front wall 906 of the lip 900 and such that the concave bearing surface 952 faces rearward and is exposed within the opening 902 of the lip 900. The bearing surface 952 will be positioned so as to engage a wedge in the finally assembled coupling assembly, as will be described in more detail below in conjunction with
Like shrouds 106, shroud 1000 in
Then, the shroud 1000 is fit over lip 900 with insert 950 already in opening 1008 of the shroud 1000. This action is generally illustrated in
At this time, the wedge 350 is inserted into the opening 1002 (shown generally in
In use, as the wedge 350 is tightened and a wider portion thereof is forced into the openings 902 and 1002, the pivoting insert 950 will move with respect to the front wall 906 of the lip 900 thereby forcing rotation of the spool 950 about mounting corner 904a. This action forces the shroud 1000 against the lip 900 in a manner generally similar to that described above in conjunction with
As described above, one of the major advantages of coupling assemblies in accordance with examples of this invention relates to the large amount of take up available when these coupling systems are used. While providing relatively compact and internally contained coupling systems (i.e., the coupling assemblies may be completely or substantially internally contained within openings provided in the components to be coupled together), coupling systems in accordance with examples of this invention still facilitate large amounts of movement between the parts to be coupled (e.g., left-to-right movement of the shroud with respect to the lip in the examples described above in a range of, for example, 0.5 to 2 inches). While this feature advantageously avoids or substantially reduces the need to build up the lip as described above, it provides other advantages as well. For example, this large take up feature also allows for more manufacturing dimensional variation in manufacturing various parts of the coupling assembly and/or the openings in the parts to be coupled (i.e., the wedge can be tightened to the extent necessary to take up the gaps and securely hold the various parts together). These features also aid in the assembly and disassembly of the coupling because (a) the various parts can be relatively loosely fit together until the final tightening step is completed and (b) the various parts can be made relatively loose when the wedge is loosened so that disassembly is easy.
Also, while aspects of the present invention have been described above in connection with use of rotatable threaded wedges, this is not a requirement in all systems and methods according to this invention. Rather, if desired, at least some advantageous features of this invention may be realized when used with a conventional “driven-in” (or hammered in) wedge or a known fluted wedge. For example, if desired, a hammered wedge may be used in combination with a spool (e.g., like spool 200 or other spool structures as described above), insert (e.g., like insert 250 or other insert structures as described above), and/or resilient member (e.g., like member 302 or other resilient member structures as described above). While such a system would not be hammerless (and would lose benefits of some examples of this invention), such a locking system would still enjoy the increased take up advantages as described above. Accordingly, at least some aspects of this invention relate to use of one or more of the various locking mechanism parts described above with driven-in, pried-in, and/or fluted wedges.
The present invention is described above and in the accompanying drawings with reference to a variety of example structures, features, elements, and combinations of structures, features, and elements. The purpose served by the disclosure, however, is to provide examples of the various features and concepts related to the invention, not to limit the scope of the invention. One skilled in the relevant art will recognize that numerous variations and modifications may be made to the example structures and methods described above without departing from the scope of the present invention.
This application claims priority benefits based on U.S. Provisional Patent Application No. 61/326,155, filed Apr. 20, 2010 and entitled “Pivoting and Releasable Wedge-Type Coupling Assemblies.” This earlier priority application is incorporated herein by reference in its entirety.
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