Armored Rigging System
Pending Publication Date: 2020-03-26
CAMPBELL RICHARD V
5 Cites 1 Cited by
AI-Extracted Technical Summary
Problems solved by technology
The bucket itself often weighs many tons.
The bucket assembly is operated in a brutal environment.
Such chains are quite heavy.
The size and weight of the chains make them difficult and dangerous to handle.
In addition, the chains rapidly elongate while in use—primarily because of link-to-link abrasion.
This elongation alters the dumping geometry of the bucket assembly and reduces its performance.
In addition to the hostile environment created by dropping, dragging, and lifting the bucket, one must also consider the hazards of deliberately laying the assembly on the ground.
The spreader bar may weigh several tons and even the dump block assembly may exceed one ton in weight.
Thus, the reader will perceive that even though the tensile members in the upper and/or lower hoist assemblies lie above th...
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[0134]Filler layer 53 preferably selected for its compressive strength and toughness. However, it should be mom pliable than either the stranded core or the armor layer. It is preferable for the filler layer to provide cushioning, both to blunt the impact of lateral blows and to help create larger bend radii for the core strands. Suitable materials include cross-linking urethane, synthetic rubber, natural rubber, gel material, and closed or open-celled foams. In fact, if the end fittings and armor layer provide suitable sealing, the compressive layer may even be a gas such as air or nitrogen. It could also be a liquid. Such fillers may also be used to provide a battier against harmful debris that have penetrated the armoring layer.
[0135]FIG. 7 shows a tensile member made using this construction that is bent around edge 68 (such as exists proximate top rail 38 of the dragline bucket). Filler layer 58 is able to compress to effectively create a larger bend radius for stranded core 54. Armor layer 56 experiences a smaller bend radius. The critical bend radius for the stranded core will differ according to the material and construction used for the stranded core. The term “construction” refers to how the strands within the core are arranged (parallel strands, helically-wound strands, woven strands, hybrid constructions, etc.). In general, the term “critical bend radius” means the minimum radius around which the stranded core may bend without suffering plastic deformation of at least some of its components. For most synthetic strands, the critical bend radius under low load is greater than ¼ the radius of the stranded core itself. For metallic strands the critical bend radius is larger—typically greater than the radius of the stranded core itself.
[0151]Returning to FIG. 16, the reader will note that the dump rope is not directly connected at either end in this example. Proximate drag socket 34, the connection is made via drag socket rigging assembly 120 (including a chain segment and additional components). Proximate the bucket arch, the connection is made via arch rigging assembly 118. Additional components are used at each end to facilitate the operation of the dump rope as well as its ...
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[0026]The present invention comprises an assembly and method for using a flexible tensile member as part of the rigging for a heavy machine such as those used in the mining industry. The inventive tensile member includes a core surrounded by a separate armor layer. The armor layer assumes various forms, including a hollow cyl...
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An assembly and method for using a flexible tensile member as part of the rigging for a heavy machine such as those used in the mining industry. The inventive tensile member includes a core surrounded by a separate armor layer. The armor layer assumes various forms, including a hollow cylinder having a substantial wall thickness. The core produces excellent strength in tension (and with a substantial reduction in weight). The armor layer protects the core from external blows and forces produced by the weight of the other parts of the machine's rigging and the hostile environment in which the machine operates.
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[0130]FIG. 6 shows a cross section of an armored tensile member made according to the present invention. Stranded core 54 carries the tensile bad. This stranded core preferably comprises advanced synthetic filaments. Examples of such advanced synthetic filaments include DYNEEMA, SPECTRA, TECHNORA, TWARON, KEVLAR, VECTRAN, PBO, carbon fiber, and glass fiber. In general the individual filaments have a thickness that is less than that of human hair. The filaments are very strong in tension, but they are not resistant to battering and cutting forces. Hence, they have not traditionally been used in hostile environments such as the mining industry.
[0131]The core in the example of FIG. 6 includes seven separate strands (six strands around one center strand). Each of these strands include the aforementioned synthetic filaments. The strands are often braided or twisted into a known pattern. They may also contain more traditional constituents (such as steel wires). A cable or strand including both synthetic and metallic components is sometimes referred to as a “hybrid.” The present invention applies to hybrid constructions as well.
[0132]Every group of core strands has a “critical radius.” If the group is bent around a radius that is smaller than this critical radius, at least some of the strands within the group will be plastically deformed. An objective of the present invention is ensuring that the core strands of each tensile member do not undergo a bend that it tighter than the applicable critical radius during normal operations.
[0133]In this example stranded core 54 is surrounded by filler layer 58 and the entire assembly is surrounded by armor layer 56. The diameter of the stranded core may be as small as 0.500 inches for synthetic strands. The diameter of the stranded core may also be 8 inches or even larger.
[0134]Filler layer 53 preferably selected for its compressive strength and toughness. However, it should be mom pliable than either the stranded core or the armor layer. It is preferable for the filler layer to provide cushioning, both to blunt the impact of lateral blows and to help create larger bend radii for the core strands. Suitable materials include cross-linking urethane, synthetic rubber, natural rubber, gel material, and closed or open-celled foams. In fact, if the end fittings and armor layer provide suitable sealing, the compressive layer may even be a gas such as air or nitrogen. It could also be a liquid. Such fillers may also be used to provide a battier against harmful debris that have penetrated the armoring layer.
[0135]FIG. 7 shows a tensile member made using this construction that is bent around edge 68 (such as exists proximate top rail 38 of the dragline bucket). Filler layer 58 is able to compress to effectively create a larger bend radius for stranded core 54. Armor layer 56 experiences a smaller bend radius. The critical bend radius for the stranded core will differ according to the material and construction used for the stranded core. The term “construction” refers to how the strands within the core are arranged (parallel strands, helically-wound strands, woven strands, hybrid constructions, etc.). In general, the term “critical bend radius” means the minimum radius around which the stranded core may bend without suffering plastic deformation of at least some of its components. For most synthetic strands, the critical bend radius under low load is greater than ¼ the radius of the stranded core itself. For metallic strands the critical bend radius is larger—typically greater than the radius of the stranded core itself.
[0136]Returning to FIG. 6, the reader will note the relative thickness of armor layer 56. The armor layer preferably provides sufficient protection against crushing, cutting, abrasion, impacts, bending, or any other force that could plastically deform some portion of the stranded core. The armor layer may also be used to prevent harmful debris from wearing the tensile member. The armor layer will often be greater than 0.100 inches thick and may exceed 2 inches in thickness. It may be made as a single layer or may be made as multiple layers. Many materials may be used for this layer, including natural rubber, synthetic rubber, high-density polyethylene, and fiber-reinforced materials. In some applications where a larger minimum bend radius can be tolerated, even stiffer materials (such as some urethanes) can be employed for the armor layer.
[0137]The armor layer can assume many forms. FIGS. 8(A)-(C) provide a few examples of these. FIG. 8(A) shows a woven or braided fiber cover 94 (such as commonly used on synthetic fiber ropes). FIG. 8(B) shows a covering of helically wound strands 96 (such as use for armoring wires). FIG 8(C) shows a covering made of a helically wrapped tube of tough plastic 98 (such as used on hydraulic hoses). Fiber-reinforced rubber tubing may also be used. Many other “armoring” covers could be used, including the use of hardened steel.
[0138]FIG. 9 show's a tensile member created by adding a termination 64 to each end of stranded core 54. Each of these terminations includes a transverse opening 69 configured to receive an attaching pin or other device for connecting the tensile member to external components. These terminations are joined to the tensile member using a variety of techniques, including potting, swaging, spike-and-cone connections, weaving around a grommet, etc. While the details of how-such terminations are attached is beyond the scope of this disclosure, the interested reader is referred to my U.S. Pat. Nos. 7,076,853, 7,536.754, 7,669,294, 7,818,849, and 8,215,886 These patents are hereby incorporated by reference. Termination 64 is representative of many different types of attachment components and should in no way be viewed as limiting.
[0139]Flexible overmold 70 is tire armoring component in this construction. The term “overmolding” refers to molding a suitable molded material (such as a polymer) over the top of the exterior surfaces of a previously-created assembly. The over-molded layer provides rigidity and armoring. Once the assembly of stranded core 54 and the two terminations 64 is completed, the assembly is placed into a mold cavity. A suitable molding compound is then injected around the assembly. The molding compound transitions from a liquid to a solid to form flexible overmold 70. The material used for the flexible overmold should provide suitable impact cushioning, cut resistance, abrasion resistance, and the desired compressive strength (the bend-limiting feature). Various natural and synthetic rubbers may be used for this purpose. HDPE may also be used. In some embodiments the overmold may be created as multiple layers bonded together.
[0140]The flexible overmold includes transverse holes aligning with the two transverse openings 69. From the exterior, the assembly may appear to be a unified piece made of the overmold material as the internal components will often not be visible. However, the use of stranded core 54 allows the assembly to carry a tensile load that is at least an order of magnitude greater than would be possible using the overmolding material alone (and will in most cases be several orders of magnitude greater).
[0141]The use of overmolding also allows the creation of a “pre-bent” shape if desired. The embodiment of FIG. 9 shows an overmold created with a straight stranded core. One could also bend the stranded core into a “dogleg” configuration and place the bent stranded core into a mold cavity that includes a corresponding “dogleg.” Once the overmolding process is completed, the assembly will have a dogleg shape. When the tensile member is attached to the bucket assembly the dogleg shape will be pulled straight under tension. However, when the tension is removed the tensile member will naturally seek to return to the dogleg shape and this action will make it tend to bend in a predictable direction and to a predictable extent. Of course, this type of pre-bent configuration could be accomplished in many different ways, including the use of pre-tensioning strands.
[0142]FIG. 10 shows an overmolded assembly that is made with a different type of internal construction. In this construction one or more individual synthetic fibers are wound many times between two metal eyes 72 to create wound fiber core (74) (The fibers are not shown in the middle of the view as the lines become too close together). The fibers may be placed in a flexible binding material to retain the desired position and orientation. Once this is complete the assembly is placed in a mold cavity and a flexible overmold is added as for the embodiment of FIG. 9.
[0143]The stranded core could be made in many additional ways. It could be made as a spliced rope, a fiber sling, a round rope sling or grommet, a steel cable, and a composite of multiple materials and/or multiple tensile members. Any of these constructions could be made into an overmolded assembly. As one example, a spliced rope can be made by passing a length of a stranded core around a fixture and then weaving the stranded core back into itself. This process is described in detail in co-owned U.S. Pat. No. 9,791,337 (such as in FIGS. 1 and 2 of that patent). U.S. Pat. No. 9,791,337 is hereby incorporated by reference into the present disclosure.
[0144]FIGS. 11-13 show still another wav to provide the desired toughness, compressive strength, bend-limiting features, and suitable armoring. The flexible tensile member shown is provided with a series of abutting bumpers 100. FIG. 12 shows a detailed sectional view through this assembly. The adjoining bumpers may be provided with a large radius 102. This allows the tensile member to bend somewhat before the adjacent bumpers run into each other. The bumpers may be made of a tough and flexible material such as synthetic rubber, with or without reinforcing fibers. They may also be made of a more rigid material, such as hardened steel or aluminum. The segmented components could lake on many different forms, including the use of interlocking or other advanced features.
[0145]FIG. 13 shows more possible features that may be included in such an assembly. Each bumper 100 includes a sleeve 104 configured to slide along the exterior of stranded core 54. The sleeves 104 may be joined together into one continuous sleeve (either by joining the individual segments or by providing one long sleeve to which multiple bumpers are attached). The use of a continuous sleeve tends to prevent the ingress of contaminants into the area of the stranded core.
[0146]Each free end of the stranded core is polled into a termination 64 via potted volume 106 in the example shown. The portion of each termination facing the bumpers is given flange 108—so that the termination bears against the first bumper over a large surface area. The reader will thereby appreciate how the inclusion of the bumpers and the flange armors the tensile member against lateral compression blows and sharp edges, and also limits the bending of the tensile member. In other embodiments the sleeve may also be bonded to the termination at either end. Using this approach, there is continuous protection of the stranded core from end to end.
[0147]The preceding embodiments have shown the armor layer as being essentially uniform from one end of the tensile member to the other with a constantly-bending structure (and uniform armoring) this need not always be the case. FIG. 14 shows an embodiment in which one end of the tensile member is made stiffer than the other (and provided with greater armoring). The entire length of the exposed core strands is surrounded by armor layer 56, which provides a first degree of compressive stiffness. Secondary armor layer 116 is provided over only a portion of the tensile member. It provides even greater compressive stiffness for a portion of the tensile member. The presence of this greater stiffness may be used to control how the tensile member will deflect. The presence of the additional armoring may be used to address abnormal pinch, cut, or wear concerns existing over only a portion of the tensile member's length.
[0148]In addition, the extra armoring may be provided at some intermediate point rather than on one end. One example is the application to a power shovel, where the additional armoring might be provided for the length of a hoist cable that passes around the top sheave.
[0149]In some instances a length of armored synthetic cable may be combined with a length of chain. FIG. 15 shows this combination. A short chain segment 110 is connected to termination 64. Armor layer 56 extends right up into the termination in this example. Other types of end fittings can be used.
[0150]FIG. 16 shows an inventive armored tensile member being used as a dump rope in a dragline bucket assembly. The example shown combines many optional features. Dump rope 26 is constructed using the core layer and armor layer described previously (possibly including a tiller layer as well). One end of the dump rope is connected to drag socket 34. The opposite end is connected to arch 32. In between, the dump rope passes around dump block 28. The connection to the drag socket and the arch may be direct or indirect. In the example shown, the dump rope is connected to the drag socket via a chain segment 110. This connection could also be made via a splitter assembly 37 such as shown in FIG. 3.
[0151]Returning to FIG. 16, the reader will note that the dump rope is not directly connected at either end in this example. Proximate drag socket 34, the connection is made via drag socket rigging assembly 120 (including a chain segment and additional components). Proximate the bucket arch, the connection is made via arch rigging assembly 118. Additional components are used at each end to facilitate the operation of the dump rope as well as its removal and replacement.
[0152]FIGS. 17-20 show one exemplary embodiment of a dump rope connection using the inventive armored cable. Many other embodiments are possible, but the one illustrated serves to illustrate the general concepts. FIG. 17 shows a sectional elevation view through one end of the dump rope. The core strand layer has been terminated by placing a length of free strands 128 inside expanding cavity 124 in anchor 122. This length is then locked in place using potting compound. The potting compound hardens around the strands in the expanding cavity and creates a solid “plug” that prevents the strands being pulled free of the expanding cavity. The attachment of the anchor to the cable creates a “termination.”
[0153]Anchor 122 in this example is radially symmetric about the cable's central axis. It may, for instance, be a metal object that is turned on a lathe or an automatic screw machine. Anchor 122 may also include an expanded receiving cavity that receives a portion of armor layer 56 as shown. The overlap between the anchor and the armor layer prevents any portion of the core strands being exposed to the outside environment. It also serves to positively locate the armor layer along the longitudinal axis.
[0154]The reader will note that anchor 122 includes a step in its outer diameter. This step creates load flange 130. Load flange 130 is useful in transferring a tensile load to the cable. FIG. 18 shows an exploded perspective view of arch rigging assembly 118. Load flange 130 is clearly visible on anchor 122. Clevis fitting 132 is designed to connect anchor 122 to the arch of the drag line bucket. It includes cylindrical receiver 138 which is sized to slidably receive the larger diameter of anchor 122. Load flange 140 surrounds the opening of receiver 138.
[0155]Load flange 130 on anchor 122 and load flange 140 on clevis fitting 132 are sized so that both may be engaged by split clamp 142 when anchor 122 is slid into clevis fitting 132 and split clamp 142 is closed over the assembly. Clamp pins 144 are passed through holes in the split clamp and into pin receivers 146 in clevis fitting 132 in order to lock the split clamp in place and unite the assembly. Clevis pin 136 can be slid through transverse opening 134 to connect clevis fitting 132 to a tang mounted on the bucket arch.
[0156]FIG. 19 shows a sectional elevation view through the arch rigging assembly in an assembled state. The word “proximal” shall be used to describe a position more toward the center of the length of the dump rope (toward the left in FIG. 19) while the word “distal” shall be used to describe a position more away from the center of the length of the sump rope (toward the right in FIG. 19). The reader will note that the proximal portion of split clamp 142 closes over load flange 130 on anchor 122 while the distal portion of the split clamp closes over the distal-facing surface of load flange 140 on clevis fitting 132. Anchor 122 is thereby secured to clevis fating 132.
[0157]FIG. 20 shows a perspective view of the completed assembly. Anchor 122 has been secured to clevis fating 132 by split clamp 142. Clevis fitting 132 has been secured to arch 32 by passing clevis pin 136 through both the clevis fitting and tang 144 (tang 144 being welded to the arch). Thus, the assembly connects the inventive dump rope to the arch.
[0158]The multi-component attachment offers some advantages and is therefore preferred. It is expected in the normal operation of the dragline system that dump rope 26 will need to be replaced. It is hoped that the replacement cycle could be as long as 21 days for a constantly operating dragline crane, but the cycle may be shorter. In order to replace the dump rope the bucket assembly is laid down. Clevis fitting 132 is likely a heavy piece of steel. It is advantageous to leave it attached to the bucket arch, as it is likely to heavy for a human technician to lift (at least without substantial risk of injury).
[0159]The technician does not need to remove the clevis fitting in the assembly of FIG. 20. Instead, the technician removes the fastening(s) securing split clamp 142 in place and opens the split clamp. The split damp preferably remains connected to the clevis fitting so that the technician does not have to remove it. Once the split clamp is opened, the technician slides anchor 122 clear of clevis fitting 132. The technician then performs a similar operation for the fitting located on the other end of the dump rope.
[0160]The use of synthetic strands allows the dump rope to be much lighter than the prior art designs. Even with an anchor 122 attached at either end, the dump rope is still light enough for human operators to lift and remove it without the need for a crane or other heavy equipment. A new dump rope is then installed in place of the old one by slipping the new anchor into clevis fitting 132 and closing and securing split clamp 142.
[0161]Returning briefly to FIG. 19, it is significant for the reader to understand that the attachment of anchor 122 to the core strands is typically done off-site in a controlled environment. For example, if potting is used to create the termination, the orientation of the components and the environmental conditions significantly impact the strength of the connection. Thus, it is desirable (though not essential) to create the termination off-site. The use of the separate clevis fixture means that only the portions of the dump rope assembly that are important to the creation of the termination need to leave the job site. The fixtures for both ends of the dump rope typically remain attached to the bucket and the drag line, respectively.
[0162]Of course, the fixtures used to connect the dump rope will eventually wear out. These are larger and heavier items that may well require a crane to remove and reinstall However, even if they must be replaced every 90 days an advantage of the inventive dump rope assembly is apparent. Most dump rope replacement operations will only involve the dump rope and its affixed anchors. Only occasionally will the end fittings need to be replaced.
[0163]Returning now to FIG. 7, some additional significant aspects of the present invention will be discussed. FIG. 7 shows the extreme example of the inventive dump rope being bent around an edge 68. The three layers (stranded core 54, optional filler layer 58, and armor layer 56) experience differing degrees of deformation. This difference will tend to make the components slip (longitudinally) relative to one another.
[0164]Another example is the passing of the cable around a pulley or top sheave. The pulley preferably includes rounded edges and other features allowing a smooth transition. Even so, since the dump rope at times carries a substantial tensile load, the forces within the rope will be significant in the vicinity of the pulley. The outer surface of the armor layer will frictionally engage the pulley, meaning that the armor layer will carry some tensile load whether it is desirable or not.
[0165]It is possible to tightly lock the armor layer to the stranded core. For example, one can deposit the armor layer over a wrapped or braided core so that the armor layer material (while still a liquid transitioning to a solid) flows in and around the surface variations of the stranded core and creates a mechanical interlock. The strength of this interlock, may or may not be sufficient to prevent slippage between the armor layer and the stranded core, but it will certainly minimize slippage.
[0166]One might wish to design a core structure and use an armor material that would create a very strong core-to-armor bond. However, doing so would compromise one of the desired advantages of a multi layer structure. Allowing some slippage between the layers permits the armor layer to protect the stranded core. Looking again at FIG. 7, if no slippage is allowed between the armor layer and the stranded core in this example then the stranded core must bend tightly around the edge. Allowing some slippage produces a more gradual bend In the stranded core, which is desirable.
[0167]Thus allowing some slippage between the layers in the inventive dump rope is desirable. However, it is also preferable to ultimately limit the slippage in order to extend the life of the rope. Consider what might happen in the absence of a slippage limitation—The armor layer will frictionally engage the dump block pulley and progressively be pulled toward one end of the rope. It may be bunched at one end like a sock and leave the opposite end unprotected. In order to minimize this possibility, it is preferable to positively terminate both the stranded core and the armor layer. If a filler layer is present it may need to be positively terminated as well.
[0168]As explained previously, an anchor is attached to each end of the stranded core to create a termination (The word “termination” generally meaning something connected to the dump rope that is capable of transmitting force to or from the dump rope). A good approach is to connect both the stranded core and the armor layer to the anchor used in the termination. FIG. 21 illustrates one example of how this may be done. This figure shows a radially symmetric anchor used to create a termination (radially symmetric about a central axis aligned with stranded core 54). In FIG. 21, anchor 150 includes a conventional expanding cavity 124. A length of strands is placed in this cavity and potted to create potted volume 106. Stranded core 54 is thereby connected to anchor 150. The use of potting is not the only way to create such a connection, but it is certainly a good way.
[0169]Anchor 150 may contain other conventional features such as load flange 130. The load flange may be sued to secure the anchor to something like the clevis fitting shown in FIG. 19. Many other features may also be added such as external threads, a clevis extension, a cross pin, etc.
[0170]As explained previously, the word “proximal” shall be used to describe a position more toward the center of tire length of the dump rope (toward the left in FIG. 21) while the word “distal” shall be used to describe a position more away from the center of the length of the sump rope (toward the right in FIG. 21). The proximal end of anchor 150 includes neck 152. The outward facing surface of neck 152 includes one or more annular protrusions 154 (The particular example includes two such protrusions). The term “neck” should be understood to mean tire proximal end of the anchor, and it is not limited to the shape illustrated.
[0171]A portion of armor layer 56 proximate the end of the armor layer is slipped ever the outward facing surface of neck 152 to create an overlap portion. A compression collar is then used to compress this overlap portion against the neck of the anchor and thereby mechanically lock it to the anchor. In this example, the compression collar assumes the form of swaging collar 148. The swaging collar is then placed over the outward facing surface of the armor layer. A swaging die is then used to tightly deform the swaging die over the end of the armor layer and compress it inward. Swaging collar 148 exerts considerable inward pressure on armor layer 56. The two annular protrusions 154“bite” into the inward facing surface of the armor layer. A strong mechanical interlock between the armor layer and anchor 150 is thereby created. A similar termination is preferably created on the opposite end of the dump rope.
[0172]The use of a compression collar is of course not the only way to mechanically lock the end of the armor layer to the anchor. Other options for mechanically locking the end of the armor layer to the anchor include: (1) providing a male thread on the anchor neck and using a threaded compression nut slipped over the armor layer and threaded onto the male thread to flare the end of the armor layer and compress it against the anchor neck; (2) placing a transverse pin or other fastener through the armor layer and the neck of the anchor; and (3) using an adhesive to mechanically bond the end of the armor layer to the neck.
[0173]Using this construction, it is possible for armor layer 56 to stretch and slip with respect to the stranded core (and the filler layer if one is present). However, the armor layer will tend to return to its starting position with respect to the stranded core when the bending and stretching forces are relaxed. Thus, a construction such fcs shown in FIG. 21 preserves the advantages provided by allowing the armor layer to move with respect to the stranded core while reducing or eliminating live disadvantages (primarily an accumulating dislocation between the layers).
[0174]The approach taken in FIG. 21 is primarily a tension-based method of minimizing slip accumulation between the armor layer and the stranded core. As a particular point on the armor layer tries to translate away from air anchor on one end of the dump rope, the portion of the armor layer between that point and the anchor will be placed in tension and this tension will tend to limit farther slippage. Of course, when tension is placed on one portion of the length of the armor layer compression will naturally be placed on another portion. The armor layer's ability to sustain compressive loadings without buckling is rattier limited, however, so the restoring force existing on the compression side is generally much lower than that existing on the tension side. For this reason, it is still correct to say that the slip minimizing approach for the embodiment of FIG. 21 is tension-based.
[0175]The reader should not assume, however, that is it impossible to create a compression-based method of limiting slip accumulation between the armor layer and the core strands. Provided that the armor layer has sufficient compressive strength, this is in fact possible. The embodiment shown in FIGS. 11-13 may properly be viewed as a compression-based approach.
[0176]FIG. 22 is a sectional view showing greater detail of the armor layer and the anchor used in a compression-based approach. Stranded cored 54 is potted into expanding cavity 124 in anchor 156. The anchor preferably includes other features such as described previously, such as load flange 130.
[0177]The armor layer tor tins embodiment includes multiple components. Armor layer 56 lies over stranded core 54 as for the prior embodiment. However, an additional armor layer is added in the form of multiple bumpers 100. The bumpers are preferably made of a resilient material such as fiber-reinforced natural or synthetic rubber. Each bumper is a “donut” of material including inner diameter 158. This inner diameter is sized to slide freely over the outer diameter of armor layer 56. Each bumper 100 also has an outer diameter 164, which is sized to pass through the dump block and any other relevant features.
[0178]Each bumper 100 includes a radius 102 facing laterally outward. Each radius on a particular bumper bears against the radius on a neighboring bumper and when these two radii are pressed together and this action increases the effective stiffness of the dump rope and limits the amount of curvature that the dump rope can undergo.
[0179]Flange 162 is included on the proximal side of anchor 156 and this creates thrust face 164 facing the first bumper next to the anchor. The interface between thrust face 164 and the first bumper creates a compression interface 160. A length of armor layer 56 is secured within anchor 156 and this tends to keep armor layer 56 in place. However, bumpers 100 are able to flex and slide a small amount along the exterior of armor layer 56. They tend to limit the amount of motion of the armor layer relative to the stranded core (since it is not possible for the relatively rigid bumpers to migrate toward one end of the dump rope like a sock). Thus, this embodiment is a compression-baaed approach. It is also possible to flexibly link the bumpers together (and to link the end bumpers to the anchors ). This limits the amount of sliding and also serves to prevent the ingress of dirt and other contaminants.
[0180]Looking again at the example of FIG. 6, some dimensional examples can be provided. In one exemplary embodiment the outward-facing surface of the stranded core (or jacket overlying the stranded core if one is present) has a diameter of 5 inches (12.7 cm). The inward-facing surface of the armor layer has a diameter of 6 inches (15.2 cm). The gap is therefore nominally 0.5 inches (1.3 cm).
[0181]Some compressive stiffness is desirable in armor layer 56 to maintain the gap. Armor layer 56 is essentially a hollow cylinder. The total length of a tensile member 46 used in the upper hoist rigging ranges from about 3 meters to 8 meters. The armor layer is just shorter than the overall length. An average armor layer is then a hollow cylinder 5 meters long with a wall thickness of 2 inches (5 cm). It is preferably made from a tough natural or synthetic rubber. It is preferably reinforced with fibers for added stiffness. The reinforcing fibers may be steel strands, glass strands, or some other suitable material.
[0182]For a tough and flexible material (such as used in the armor layer) the resistance to buckling will largely be a function of wall thickness in comparison to the overall diameter. In the example given, the overall diameter of the armor layer is 20.3 cm. The wall thickness is 5.1 cm. If one considers a transverse cross section (perpendicular to the central axis of the cylinder) the cross sectional area of the 20.3 cm diameter circle is 324 square centimeters. The cross sectional area of the wall itself is 141 square centimeters. One can define a ratio of the wall cross sectional area to the area of the circle defined by the overall outer diameter (20.3 cm in this case). That ratio for this example is 43.5%. In order to maintain enough stiffness to minimize contact between the armor layer and the stranded core, it is preferable to have this ratio exceed 25% and even more preferable to have it exceed 40%. Thus, the reader will appreciate that the armor layer will be a thick-walled cylinder.
[0183]Having provided a disclosure of tire invention and some of its applications, the following additional principles should also be known:
[0184]1.The inventive methods and hardware has been described with respect to two examples of mining machinery—power shovels and dragline cranes. However, the invention is applicable to other forms of mining machinery and beyond the mining industry as well. As an example, the invention is applicable to any field where armoring of a flexible tensile member is desirable.
[0185]2.The armor layer or layers may be made removable over some or all of the tensile member's length. This may be done to facilitate inspection of the underlying synthetic core components.
[0186]3. Some “grip” engagement between the core and tire armor layer will be desirable in some circumstances. As an example, the inward facing surface of the armor layer could be given a gripping texture (ribs or helical grooves) so that the armor layer docs not slip with respect to the core in a region where the tensile member passes over a sheave. In such a situation surface shearing forces are preferably transmitted from the armor layer to the core layer in order to prevent the armor layer slipping like a sock. It is also possible to provide outward facing gripping surfaces on the core layer or on tire jacket material surrounding the core layer.
[0187]4.Another type of gripping feature between the core and the armor layer can be cross-stitching or some form of adhesive.
[0188]5.It is desirable to provide an armor layer that indicates a breach or other significant damage to the protection it affords. As a first example the armor material may include a brightly colored layer covered by a dark layer. A gouge or a split then becomes visible as a bright portion against a dark background. For embodiments in which the armor layer is sealed to a termination at both ends of a tensile member, a brightly dyed fluid can be placed between the armor layer and the core layer. This bright fluid will seep out of any breach in the armor layer and indicate a problem.
[0189]6.An armor layer may be provided on an intermediate portion of the tensile member rather than proximate the ends. As one example, an armor layer may be provided for a region of the tensile member that passes back and forth over a top sheave.
[0190]7. An armor layer may be provided on a length of core that is passed around a spliced termination (such as a large thimble-type device) and woven back into itself. The armor layer could cover the terminated portion and the woven portion.
[0191]Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. Thus, the language ultimately used in the claims shall define the invention rather than the specific embodiments provided.
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| Property | Measurement | Unit |
| Weight | ||
| Thickness | ||
| Diameter | ||
| tensile | MPa | |
| Particle size | Pa | |
| strength | 10 |
Description & Claims & Application Information
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the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
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