The present invention pertains to a bucket for a cable shovel machine, and in particular to the door for the bucket.
As shown in
The doors can be very heavy and at times may weigh over 30,000 pounds. The door has at least one plate with an interior surface to contain the material being excavated. The door 200 is hinged to supports on the back wall so as to be closed during digging, and opened during dumping. A releasable latch is provided to hold the door 200 in the closed position. The size and weight of the door combined with the weight of the load within the cavity of the bucket causes the door to experience stress. Often the load within the bucket is not centered and causes the door to experience twisting, bending, and torsional loading. The load may become off center during loading or may become off center when the operator contacts the tracks of the cable shovel or the edges of the truck body when maneuvering the bucket. The stresses can cause the door to crack and become damaged. To strengthen the door and minimize the twisting, bending, and torsional loading experienced, the plate is generally reinforced with supports. The supports increase the door stiffness and help the door resist the off center loading. The supports, however, increase the weight of the bucket.
In use, the bucket with the door in the closed and latched position is driven into the ground to collect a load. Once filled, the bucket is lifted and the machine rotated to position the bucket over an empty truck body of a mining dump truck. The latch is released to dump the load into the truck body. The door is free swinging so that when the latch is released the potential energy of the weight of the door and the load within the bucket transitions into kinetic energy and causes the door to swing quickly and forcefully downward. The door, when released, can sometimes strike the truck body resulting in damage to the truck and/or the door. To compensate, the operator will often raise the bucket higher than necessary to avoid contact with the truck or will lower the bucket onto the truck floor or the material already in the truck before releasing the door for a more controlled opening of the door. This practice of lowering the bucket also requires an additional lifting of the bucket up out of the truck body with enough lift for the open door to clear the sides of the truck body. This extra lifting and/or lowering on every digging cycle slows the process and results in less production. A higher dumped load can also cause damage to the truck as the load dropped from a higher position impacts the truck body with more force. After the load is dumped, the operator swings the bucket away from the truck and lowers the bucket back to engage the ground. As the bucket is lowered to engage the ground the front wall approaches a horizontal position and the door approaches a vertical position, which causes the door to close under its own weight. The door will at times slam shut with great force and may cause damage to the bucket or the door. The latch, then, automatically actuates to secure the door for another digging pass.
The uncontrolled swing of the door can cause damage to mining equipment and can be dangerous to equipment operators and maintenance personnel. Many devices with varying degrees of success have been used to minimize the damage of the forceful swing of the door. For example, numerous snubbers, such as the snubber disclosed in U.S. Pat. No. 5,613,308, have been used to slow the uncontrolled swing of the door. In addition, hydraulic circuits as disclosed in U.S. Pat. No. 6,219,946, and brake and clutch devices as disclosed in U.S. Pat. No. 6,467,202 have been used to control the swing of the door. Bumpers have been used to protect the bucket as the door closes and to protect the tracks of the cable shovel if the door is opened to close to the cable shovel. The devices used to restrain and dissipate the kinetic energy of the load and the door are expensive, increase the weight of the bucket, and require intensive maintenance.
A typical latch includes several components that add considerable weight to the bucket. Each cable shovel is designed to lift a maximum weight, which is the combined weight of the bucket and the load of excavated material. Accordingly, the more weight that exists in the bucket, the smaller the load that can be gathered into the bucket or the less wear material that can be fitted to the bucket. Moreover, on account of the placement of the latch along the bottom of the door, it is common for these parts to need frequent repair or replacement because of the heavy loads and abrasive materials encountered. The latch system must be regularly adjusted to ensure that the latch fully engages the latch keeper as the latch experiences wear. Adjusting the latch bar because of wear can be very time consuming (i.e., increased downtime which translates into a decrease in productivity).
The present invention pertains to improvements in buckets for cable shovels that provide increased production, less wear and damage to the truck body and bucket, and greater safety.
In one aspect of the invention, the hinge axis for the door is located forward the exterior surface of the back wall of the bucket (i.e., the surface to which the stick is connected). This repositioning of the pivot axis results in the axis of rotation for the door being closer to the door's center of gravity which results in a smaller moment arm acting on the hinge pin and the lock or brake. The reduced moment arm allows for the door to be built with less bracing and structural robustness and may allow a smaller lock or restraint which could allow a lighter door to be utilized. This novel mounting arrangement results in a decrease in the potential energy, and creates a shallower and less forceful door swing during dumping. Because the door swing is less forceful, the door may not require snubbers or alternative devices to slow the swing of the door which further decreases the weight and potential energy of the door. A lighter door may allow the bucket to carry extra capacity or may be able to have more wear components added to the bucket. In addition bumpers may not need to be used to minimize the damage from the forceful swing of the door. As a result of the shallower and less forceful door swing, the operator can dump loads closer to the truck body for greater efficiency without the same risks of damaging the truck or other components on the cable shovel. The operator may not have to lower the bucket onto the truck floor or the material already in the truck before releasing the door which will reduce the likelihood that the operator will forget to lift the bucket sufficiently out of the truck body before swinging the bucket out of the way. The cable shovel will use less power and have less motor starting and stopping resulting in lower heat generation and wear. Removing the step of lifting the bucket out of the truck body may save 2-3 seconds from the cycle time. The reduced cycle time could increase productivity by as much as 5-10 percent.
In another aspect of the invention, the hinge members connecting the door to the shell are generally linear. A generally linear hinge member, when compared to the traditional hooked or gooseneck hinge member, reduces the stress concentrations within the hinge, reduces the amount of material in the hinge, and reduces the weight of the door.
In another aspect of the invention, improvements in the latch are provided by moving the latch location or replacing the latch with an alternative brake. In one embodiment, the door may be adequately secured in the closed position without a latch; i.e., by relying on a different kind of restraint such as a rod brake or a hydraulic circuit, which would impose less weight and/or fewer components. In another embodiment, the door may be secured in the closed position with a latch that is not in the high-stress, high abrasion bottom, front, central position where the typical latch is located. As an example, a latch may be provided on both sides of the door for less latch maintenance and a longer usable life for the latch. In another embodiment, the door may be adequately secured in the closed position with a smaller latch to impose less weight on the bucket and/or fewer components.
In another aspect of the invention, a door, a flap, and a restraint can be provided to selectively close the bottom of the bucket cavity. In some cases the door may interfere with the stick or the stick attachment supports. To overcome the potential interference, the rear of the door (i.e., the side closest to the hinge members) may be cut down to allow clearance. If the door is cut down a gap will be left in the back of the bucket (i.e., at the edge of the door closest to the back wall of the bucket) that would allow material to flow out of the bucket. A flap can be used to contain the material in the bucket and allow the material to flow out of the bucket when the door is opened. The flap can accommodate a shallower swing for a door with a hinge axis repositioned forward of the back wall when the door is retrofit in certain existing buckets or used with new buckets of the same existing design. The flap can also reduce the weight of the door on any bucket as the heavy door member covers only part of the bottom opening.
In another aspect of the invention, the door has a front portion (i.e., the portion closest to the front of the bucket and away from the hinges) that is slanted, bent, or curved inward toward the digging edge. This construction strengthens the door for greater durability and/or increased weight savings. The slant, bend, or curve creates a larger section modulus and moment of inertia to stiffen the door against bending. This construction also improves bucket loading by allowing material to move up the back of the bucket more easily. The curved door also moves the bottom end of the front wall of the bucket away from the highest wear area with only a little change in the bucket volume, which results in extended times between the need to refurbish the bucket.
The present invention pertains to a bucket 10 for a cable shovel machine. A cable shovel bucket 10 includes a frame or shell 11. Shell 11 includes a rear end with a back wall 12 having attachment supports 17 to attach the bucket to earthmoving equipment, a front end with a front wall 13 opposite the back wall 12, and a pair of opposing sidewalls 14 each located between the back wall and the front wall. The shell may be constructed with walls having a single plate or may be constructed with portions of the bucket having double plates as is well known. If the shell is constructed with double plates, a top wall and a bottom wall 26 may be provided to connect the double plates. A door 16 with an interior surface and an exterior surface 36 is provided to define a bottom wall of the bucket (
The shell walls 12-14 are interconnected to define a generally rectangular periphery. Each of the shell walls 12-14 includes an interior surface 18-20, i.e., back surface 18, front surface 19 and side surfaces 20. Door 16 includes a bottom interior surface 21. The interior surfaces 18-21 collectively define a cavity 24 into which the excavated material 25 is collected during digging (
In the present invention, the pivot hole and the hinge axis 46 of bucket 10 is forward of the exterior surface 47 of back wall 12 (i.e., the exterior surface of the bucket that faces the cable shovel when the bucket is in the dumping position) and closer to the collective center of gravity CG for door 16 and the load in the bucket (
The repositioning of hinge axis 46 forward of exterior surface 47 of back wall 12 will result in a shallower and less forceful swing for door 16 when the load is dumped. In a shallower swing, the bottom edge 48 of door 16 moves a shorter distance from shell 11 when the door moves from its closed position to its open position compared to a conventional door 200 secured rearward the exterior surface of the back wall of the bucket. This is illustrated in
This shallower swinging of door 16 lessens the risk the door will strike the truck body during dumping without restricting the discharge of the load. The repositioned hinge axis 46 causes the door to move with less force and speed when opened so that if the door unintentionally strikes the truck body, there is less risk of damage to the truck body and the door. As a result, the shallower swing also enables the bucket to be positioned closer to the truck body for dumping, which results in greater productivity and reduced risk of damage to the truck body because of a shorter distance for the falling load (
In the illustrated example (
In an alternative embodiment (
Conventional door 200 (
A conventional latch 214 can be used in connection with door 16 or door 316. Nevertheless, a conventional latch 214 has disadvantages. For example, latch bar 216 and the latch channel are positioned along the front edge 230 of the door to provide sufficient resistance to the high forces that are the result of receiving a heavy load in the bucket. The center portion of the door near the front wall 13, however, is a high wear and high maintenance area on account of the abrasive material that passes by the components each time a load is dumped. Earthen material is prone to lodging in the latch channel and guide structure 218, requiring stoppage of the digging to clean out the material and free the operation of the latch bar. Further, latch 214 is a substantial assembly with a number of components. The latch bar 216 and other components are large, robust members to provide sufficient resistance to the heavy loads resulting from maintaining the door in a closed position with material contained within the dipper body, and from material striking the door during the digging portion of the operation. The heavy weight of the latch components adds considerable weight to the bucket, and reduces the load that can be gathered in the bucket during digging or the amount of wear material that can be fitted on the bucket. Reduced weight in the bucket and greater material loads may lead to higher production if the trucks are otherwise under filled; i.e., it is desirable for the buckets to fill the truck bodies in one or more full dumps of the bucket. Reduced weight in the bucket may also enable the addition of increased wear material for a longer usable life.
Since the forward repositioning of hinge axis 46 requires less resistive force to keep the door closed, a conventional latch 214 may not be needed, though the inventive door could include a conventional latch. Alternatively, a brake 56 can be used in lieu of a latch to prevent unintended opening of the door. In one example (
In another alternative (
The elimination of latch 214 results in a reduction in the bucket weight, which leads to greater loads or the ability to secure more wear material to the bucket. The elimination of latch 214 also reduces the high maintenance and repair needs associated with the latch, and results in a means for holding the door closed (e.g., brake 56 or 56a ) with a longer usable life. Further, the brake can be used to function as both a snubber and a lock. Using the brake for both purposes permits the elimination of a separate snubber, which is typically provided. A snubber is normally an apparatus that dampens the swing of the door by friction on rotating disks. Elimination of a separate snubber leads to less cost, weight and maintenance.
In an alternative construction (
In the illustrated alternative, a latch 86 is provided with at least one lateral latch bar 88 that moves so that each end, laterally beyond the sides 90 of door 75, is received in latch channels (not shown) secured to the sidewalls 92 of shell 82. The latch bar 88 can be moved by a rotary mechanism (not shown). Numerous types of rotary mechanisms and methods for operating the rotary mechanisms are widely known. For example, the rotary mechanism could move two latch bars 88 hooked (not shown) to the same driver, one on top of the driver the other on the bottom of the driver, so that the free ends of each latch bar 88 moves laterally outward or inward to latch or unlatch the door. In an alternative example, one latch bar 88 could pivot in the middle of the door with one latch bar end going down on one side and the latch bar end going up on the other side. In this example one latch channel would have an opening that faced towards the front end of the bucket to accept the latch bar moving upwards and one latch channel would have an opening that faced towards the rear end of the bucket to accept the downwardly moving latch bar. Using one latch bar 88 ensures that both ends of the latch bar move the same distance and minimizes the likelihood that one of the latch bars would become hung up and not allow the door to fully latch.
Latch 86 may have a spring mechanism so that when the door closes the bar is deflected in a rotational manner against the biasing action of the spring, and then springs back to engage the latch channels and held in place by the biasing spring. The latch could be unlatched by a trip cable that overcomes the spring bias. In an alternative, the latch bar could be asymmetrical relative to its pivotal connection so that the latch bar by gravity returns to a predetermined position to hold the latch bar in the latch channels. In still another alternative, a hydraulic actuator could push the latch bar into a locked position. These are but examples of latching mechanisms and the latching mechanisms could be used individually or could be used in various combinations. Repositioning of the latch from the bottom of the door to the sides 90 results in less clogging, reduced maintenance needs as the latch is outside of the high wear area of the bucket, and a longer usable life for latch 86 as compared to latch 214.
Latches 214 and 86 are shown with doors 200 and 75 that are coupled to the bucket shell via conventional hinges 204 and 84. Latches 214 and 86 could be used with an inventive hinge 30 or 332 with a hinge axis 46 that is forward of back wall 12. In a construction with such a repositioned hinge axis 46, less force is needed to resist the opening of the door. As a result, the components of the latch can be smaller in size and have a smaller collective weight as compared to the conventional latches. The latch, or restraining mechanism, can also be moved away from the lower portion of the door because less total resistive moment is needed to retain the door in a closed position, as in latch 56, 56a , and 86. As noted above, a lower weight bucket enables the collection of a larger load in cavity 24 and/or the addition of more wear material.
In another aspect of the invention (
The various aspects of the invention can be used with each other or independently. As examples only, a door with a curved bottom end could be used with hinge members that place the hinge axis forward of back wall of the bucket, and a flap could be used with any of the bucket designs.
This application claims priority benefits to U.S. Provisional Patent Application No. 61/696,971 filed Sep. 5, 2012 and entitled “Bucket for Cable shovel,” which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61696971 | Sep 2012 | US |
Number | Date | Country | |
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Parent | 14013973 | Aug 2013 | US |
Child | 15600488 | US |