Patent Application
20230099091
Some implementations relate generally to dragline buckets, and, more particularly, to an optimized trunnion for a rear taper dragline bucket.
Draglines are mining machines used in surface mines to move dirt or other material. A prolific use of draglines is in coal mines where layers of dirt on top of, and in between, coal seams are removed by the dragline after which other machines, like hydraulic shovels, rope shovels and wheel loaders are used to dig and load the coal. Draglines are relatively cheap to use in terms of the energy utilized to move one cubic yard of dirt.
A typical dragline is a mining machine consisting of a long boom that is angled about 40° relative to horizontal (e.g., the ground), which is attached to the front of a rotating machinery house that can move with typical caterpillar tracks, or with specially designed feet. A dragline bucket is attached to, and suspended from the boom by, two sets of wire ropes, each of which is coiled over a respective large motorized, rotating drum. Rotating the drums causes the length of the extended ropes to change. One set of wire ropes extends horizontally outwards from the machinery house and is used to drag the bucket through the dirt or spoil in order to fill the bucket. The second set of wire ropes runs along the boom over provided sheaves and is used to hoist the bucket after it is filled. The filling action is called ‘drag’ and the hoisting action is called ‘hoist’, with the applicable wire ropes therefore called ‘drag ropes’ and ‘hoist ropes’ respectively. The set of drag and hoist ropes can consist of anything from a single rope to up to four parallel ropes or more.
Operating Phases
The typical dragline operating cycle is defined by four phases. The first three phases are 1) placing the bucket at the intended dig location and dragging it to fill, 2) hoisting and then 3) swinging the bucket into position for dumping the load. The fourth phase is to ‘dump’ the bucket so that the dirt is expended from the bucket at a desired dump location. The operating cycle then moves back into the first phase, that of swinging and lowering the bucket to the intended dig location.
Rigging
Between the bucket and the wire ropes is a collection of steel chains and components, which makes up what is called the ‘dragline rigging’, with the ‘hoist chains’ being an extension of the hoist ropes, and the ‘drag chains’ being an extension of the drag ropes. The use of chains is to prevent wear damage to the ropes as the bucket moves through the dirt, as well as to facilitate the ‘dump’ phase. The dump rope is a wire rope connection between the front of the bucket and the drag chains, via a sheave. Tension on the drag chains places tension on this dump rope which in turn holds the bucket at a specific orientation to prevent spilling of the dirt from the bucket while it is being hoisted. Relaxing of this tension on the drag ropes by releasing the ropes, releases tension on the dump rope which allows the bucket to pivot forwards (dumps) and expel the dirt downwards. This the dump action is provided by the rigging components which allow the bucket to pivot forward.
Hoist Ropes and Hoist Chains
With a dragline that has multiple hoist ropes, the ropes are spaced a certain distance apart which is determined by the distance between the sheaves on the furthest point of the boom—called the boom point sheaves. This distance is usually in the order of 4 to 8 feet depending on the size of the machine. The hoist chains are connected to the hoist ropes with steel components (e.g.,
Dragline Bucket, Trunnion and Spreader Bar
A typical dragline bucket (e.g.,
Trunnion and Trunnion Link
The component which links the hoist chain 202 with the trunnion 120 is called the trunnion link (206) and has a longitudinal shape with a clevis with a transverse hole at the trunnion end, and clevis with a transverse hole at the other end, which attaches to the chain. The clevis on the lower side fits into a corresponding clevis in the trunnion 120 and the coupling is provided by a pin which is called the trunnion pin (208) which passes through the transverse hole in the clevis of the trunnion through the transverse hole in the clevis of the trunnion link. On the other end (the chain end), the trunnion link is coupled to the clevis of the chain stud end link, which can fit the clevis on the trunnion link. The coupling between the trunnion link and the chain is also provided by a pin.
Spreader Bar
The spreader bar keeps the two hoist chains apart so that the bucket can pivot between the chains during the dump action. The length of the spreader bar is selected so that the spreader bar keeps the hoist chains from touching the bucket top rail and prevent wear on the top rail as the bucket pivots during the dump action. The bucket pivots because of the rotation allowed between the trunnion pin, which is kept stationary inside the clevis of the trunnion, and the trunnion link, which is connected to the hoist chain. For this reason, the trunnion link has a bushing installed, which is a sacrificial cylindrical component which can absorb the natural wear between the trunnion link and the trunnion pin during the rotation of each dump action. The length of the spreader bar is also selected so as to maintain the perpendicular orientation of the trunnion link to the trunnion pin during the rotational movement, hence allowing the mating cylindrical surfaces of the trunnion pin and the bushing inside the trunnion link to remain co-axial and minimize the natural wear between them. This is important as any axial mismatch of these surfaces causes significant (abnormal) wear of the trunnion link bushing and the trunnion pin. It is therefore important that the trunnion link pivots axially around the trunnion pin, which means that the mating cylindrical surfaces of the two components remain coaxial during the full rotational movement of the bucket during the dump action. The transverse hole in the trunnion clevis into which the trunnion pin is held stationary, should therefore be oriented correctly for the full rotational movement of the hoist chains during the bucket pivot in the dump action.
Dragline Bucket and Spreader Bar
A traditional dragline bucket has the basket side walls oriented mostly parallel in a front to back direction, but with an upwards taper, with the two sidewalls being further apart at the top than at the bucket floor. This upwards taper between the two side walls in a vertical direction is believed to allow the dirt to heap easier inside the bucket as it is dragged through the dirt and filled (see, e.g., U.S. Pat. Nos. 4,791,738 and 8,250,785, which are both incorporated herein by reference). This configuration has been found to be the most efficient in a wide range of digging conditions, but it does require a spreader bar of sufficient length in the rigging. The greater the upwards taper angle of the bucket sidewalls, the longer the spreader bar required to keep the hoist chains away from the bucket top rail, and to maintain the perpendicularity of the cylindrical mating surfaces of the trunnion link and the trunnion pin. However, the weight of the spreader bar remains a concern in the rigging because if the rigging weight can be reduced, then the bucket capacity can be increased, with consequential productivity increase of the dragline, and theoretically of the mining company itself.
Removing the Spreader Bar—the Rear Taper Bucket
Thus, for at least the reason above, there is a motivation in the industry to remove the spreader bar from the rigging. One innovation had the trunnions moved to the inside of the bucket, with the chains running up towards the narrow connection with the hoist ropes without a spreader bar (see, e.g., U.S. Pat. No. 4,944,102). However, this required cutting down the rear bucket wall so that the hoist chains could clear the rear top rail when the bucket is dumped. This was not a successful innovation.
A more recent innovation to remove the spreader bar entirely from the rigging involves creating a significant inwards taper in the rear parts of the sidewalls to allow for the hoist chains to still clear the bucket even if they are not being kept apart by a spreader bar (see, e.g., U.S. Publication 2009/0183397, which is incorporated herein by reference). Although this kind of bucket has different names in the industry, this document refers to this type of bucket as a rear taper bucket.
As can be seen in
Problem Description
Some current suppliers of the new rear taper bucket place the trunnion forward of the taper transition line on the vertical (or traditional slightly outward tapered) sidewall (308). A result of this is an axial misalignment of the trunnion link with the trunnion pin. With the hoist chains now running upwards at an angle towards the narrow connection of the hoist chains with the hoist ropes, and the trunnion link in line with the hoist chains but the trunnion aligned with the sidewalls, the trunnion pin and the trunnion link bushing are not coaxially anymore. As the bucket dumps this situation is aggravated and the axial misalignment increases due planar location of the sidewalls relative to the bucket floor and rear. The result of this is significant abnormal wear of both the trunnion pin as well as the trunnion link bushing. The rate of wear is significantly more which requires replacement of the trunnion pin and the trunnion link bushing, and this resulting cost of maintenance and downtime are of concern to most customers
Embodiments were conceived in light of the above-mentioned problems and limitations, among other things. The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Some implementations can include a dragline bucket comprising a basket having a first sidewall and a second sidewall a first trunnion disposed on the first sidewall, the first trunnion having a female clevis and a trunnion pin hole. The dragline bucket can also include a first trunnion link having a male clevis constructed to engage the female clevis of the first trunnion and a trunnion link hole, wherein the female clevis of the first trunnion is configured to align the first trunnion link along a first plane defined a hoist chain as the hoist chain rotates about the first trunnion from a first position to a second position during a dump phase of the dragline bucket, and a first trunnion pin constructed to be inserted into the trunnion pin hole and the trunnion link hole, wherein the trunnion pin hole and the trunnion link hole are configured to receive the first trunnion pin and to align the first trunnion pin at a first angle, wherein the first angle is perpendicular to the first plane.
The dragline bucket can further include a second trunnion disposed on the second sidewall, the second trunnion having a female clevis and a trunnion pin hole, a second trunnion link having a male clevis constructed to engage the female clevis of the second trunnion and a trunnion link hole, wherein the female clevis of the second trunnion is configured to align the second trunnion link along a second plane defined a hoist chain as the hoist chain rotates about the second trunnion from a first position to a second position during a dump phase of the dragline bucket, and a second trunnion pin constructed to be inserted into the trunnion pin hole of the second trunnion and the trunnion link hole of the second trunnion link, wherein the trunnion pin hole and the trunnion link hole are configured to receive the second trunnion pin and to align the second trunnion pin at a second angle, wherein the second angle is perpendicular to the first plane.
In some implementations, the dragline bucket can include a rear taper dragline bucket. In some implementations, the first trunnion and the second trunnion are disposed forward of a taper line of the rear taper dragline bucket. In some implementations, the first trunnion and the second trunnion are disposed at a taper line of the rear taper dragline bucket. In some implementations, the first trunnion and the second trunnion are disposed rear of a taper line of the rear taper dragline bucket.
Some implementations can include a trunnion system comprising a first trunnion configured to attach to a first sidewall of a dragline bucket, the first trunnion having a female clevis and a trunnion pin hole, a first trunnion link having a male clevis constructed to engage the female clevis of the first trunnion and a trunnion link hole, wherein the female clevis of the first trunnion is configured to align the first trunnion link along a first plane defined a hoist chain as the hoist chain rotates about the first trunnion from a first position to a second position during a dump phase of the dragline bucket, and a first trunnion pin constructed to be inserted into the trunnion pin hole and the trunnion link hole, wherein the trunnion pin hole and the trunnion link hole are configured to receive the first trunnion pin and to align the first trunnion pin at a first angle, wherein the first angle is perpendicular to the first plane.
The trunnion system can also include a second trunnion configured to attach to a second sidewall of the dragline bucket, the second trunnion having a female clevis and a trunnion pin hole, a second trunnion link having a male clevis constructed to engage the female clevis of the second trunnion and a trunnion link hole, wherein the female clevis of the second trunnion is configured to align the second trunnion link along a second plane defined a hoist chain as the hoist chain rotates about the second trunnion from a first position to a second position during a dump phase of the dragline bucket, and a second trunnion pin constructed to be inserted into the trunnion pin hole of the second trunnion and the trunnion link hole of the second trunnion link, wherein the trunnion pin hole and the trunnion link hole are configured to receive the second trunnion pin and to align the second trunnion pin at a second angle, wherein the second angle is perpendicular to the first plane.
In some implementations, the dragline bucket can include a rear taper dragline bucket. In some implementations, the first trunnion and the second trunnion are disposed forward of a taper line of the rear taper dragline bucket. In some implementations, the first trunnion and the second trunnion are disposed at a taper line of the rear taper dragline bucket. In some implementations, the first trunnion and the second trunnion are disposed rear of a taper line of the rear taper dragline bucket.
Some implementations can include a trunnion configured to attach to a sidewall of a dragline bucket, the trunnion having a female clevis and a trunnion pin hole, wherein the female clevis is configured to engage a male clevis of a trunnion link, wherein the female clevis of the trunnion is configured to align the trunnion link along a plane defined by a hoist chain as the hoist chain rotates about the trunnion from a first position to a second position during a dump phase of the dragline bucket.
In some implementations, the trunnion further comprises a trunnion link having a trunnion link hole. In some implementations, the trunnion further comprises a trunnion pin constructed to be inserted into the trunnion pin hole and the trunnion link hole, wherein the trunnion pin hole and the trunnion link hole are configured to receive the trunnion pin and to align the trunnion pin at an angle, wherein the angle is perpendicular to the plane.
In some implementations, the dragline bucket can include a rear taper dragline bucket. In some implementations, the trunnion is disposed forward of a taper line of the rear taper dragline bucket. In some implementations, the trunnion is disposed at a taper line of the rear taper dragline bucket. In some implementations, the trunnion is disposed rear of a taper line of the rear taper dragline bucket.
Some implementations can include trunnion for a rear taper dragline bucket and rigging combination where the rigging has no spreader bar. Some implementations can include a trunnion for a rear taper dragline bucket specifically placed (permanently located) on the taper transition line, in other words, the fold in the bucket side wall where the traditional vertical, or slightly upwards taper side wall, transition into the inwards rear taper, creating a fold in the side wall.
Some implementations can include a trunnion for a rear taper dragline bucket specifically placed (permanently located) on the surface of the rear taper of the bucket, or in other words placed behind the rear taper transition line which is the fold in the bucket side wall where the traditional vertical, or slightly upwards taper side wall, transition into the inwards rear taper creating a fold in the side wall.
Some implementations can include a trunnion for a rear taper dragline bucket as described herein, which has a female or male clevis where the trunnion link of the hoist chain is attached with the trunnion pin.
Some implementations can include a trunnion for a rear taper dragline bucket as described herein, which has the hole provided for the trunnion pin in the male or female clevis of the trunnion so aligned that the axis of this hole is perpendicular to a plane formed by the hoist chain on that side of the bucket as the chain rotates relative to the bucket, during the dump action of the bucket. Because the hoist chains of a bucket can change in length, the hole in the trunnion for the trunnion pin should be more or less perpendicular to this plane. Perfect perpendicular alignment of the pin hole may not be possible due to different buckets geometries, different lengths of hoist chains, and different ways of connecting the hoist chain to the hoist rope.
Some implementations can include a trunnion for a rear taper dragline bucket as described herein, specifically placed (permanently located) on the surface of the side wall of the bucket, which may also be a slightly upwards taper side wall forward of the taper transition line, which is the fold in the bucket side wall where the traditional vertical, or slightly upwards taper side wall, transition into the inwards rear taper creating a fold in the side wall.
Some implementations can include a rear taper bucket having trunnions with axially aligned cylindrical mating surfaces of the trunnion link bushing and the trunnion pin. Some implementations can include a geometrically shaped trunnion for a rear taper dragline bucket where the trunnion can be placed forward of (
In some implementations, the trunnion pin hole, in the (female or male) clevis of the disclosed trunnion is angled to be perpendicular to the plane described by movement of the hoist chain on that side of the bucket, relative to the bucket, during the dump action of the bucket, e.g., from a first position (bucket loaded) to a second position (dumping). This plane is referred to herein as the hoist chain plane for discussion purposes, and may be close to, but not necessarily on the same plane of the surface of the rear taper of the bucket. The hoist chain plane is defined by two imaginary lines made by the hoist chain, the first line (or first position of the chain) is shown in
By placing the trunnion on the taper transition line, or behind this line, it may be easier to align the trunnion pin hole in the clevis of the trunnion perpendicular with the hoist chain plane, and this location will also allow more clearance between the hoist chains and the bucket side top rail.
In operation, the trunnion link 908 male clevis is inserted into the female clevis 910. The trunnion pin hole in the trunnion link 908 and the trunnion pin hole 904 of the trunnion 902 are aligned so that the trunnion pin 906 can be inserted to secure the trunnion link 908 to the trunnion 902.
The dashed lines 1202 and 1206 are in the hoist chain planes (e.g., the plane formed by lines 802 and 804) about the trunnion pins 1204 and 1208, respectively. In general, the trunnion pin hole and bushing axis should be perpendicular to the hoist chain plane, or nearly perpendicular. The angle may not be exactly perpendicular and may not stay perpendicular as the chains and bushing wear during operation. As discussed above, different implementations can have different trunnion placement, e.g., before, on or after the taper transition line. The trunnion pin hole/bushing axis being perpendicular to the hoist chain plane remains the same regardless of where the trunnion is placed.
In some implementations, the trunnion link bushing hole can be more axially aligned with the trunnion pin during the entire rotational movement of the bucket dump action, and even if this is not achieved perfectly due to different buckets and different lengths of hoist chains, the improvement or advantage provided by the disclosed trunnion is still significant. The improvement or advantage includes reduction, or even elimination, of the abnormal wear between the cylindrical mating surfaces of the trunnion link bushing and the trunnion pin, eliminating their early replacement, hence saving on maintenance downtime and costs.
In some implementations, the trunnion pin hole in the female clevis of the trunnion should be as close to possible perpendicular to the hoist chain plane. However, perfect alignment may not be possible due to different buckets geometries, different lengths of hoist chains, and different ways of connecting the hoist chain to the hoist rope.
In some implementations, the placement of the trunnion on a dragline bucket influences the dump performance of the bucket, the force on the dump rope and consequential wear on that component and setting of the bucket carry angle. These parameters should be considered when the new invention trunnion is designed and placed on a rear taper bucket.
While some example implementations have been described in terms of one or more embodiments with one or more example modifications, it is recognized that other modifications and variations of the embodiments described above are within the spirit and scope of the disclosed subject matter. Applicant intends to embrace any and all such modifications, variations and embodiments.
