PROCESS FOR THREE-DIMENSIONAL MODELING AND DESIGN OF OFF-HIGHWAY DUMP BODIES
A method of loading material into a dump body of a truck using a loading bucket whose volumetric capacity is approximately ⅓ or more than that of the dump body is provided. The dump body having side walls that are spaced relatively wider than conventional dump bodies. The loading bucket having a gate at a lower end thereof that when free swings open and causes the material contained in the loading bucket to drop into the dump body. The method including the steps of filling the loading bucket with an amount of earthen material and centering the loading bucket over the dump body. The bucket is then lowered to a position that: (1) substantially minimizes the clearance between the floor of the dump body and the swinging gate in its freed position; (2) allows the swinging gate to clear the side walls of the dump body as it swings through an arc after it is freed, and (3) allows the material to be discharged substantially in the center of the dump body. The swinging gate is then freed so as to open the bucket and allow the material held in the bucket to drop into the dump body.
This application is a continuation of U.S. Ser. No. 13/364,878, filed Feb. 2, 2012, which is a continuation of U.S. Ser. No. 12/106,794, filed Apr. 21, 2008, (now U.S. Pat. No. 8,113,763), which is a continuation of U.S. Ser. No. 09/593,647, filed Jun. 13, 2000, (now U.S. Pat. No. 7,369,978) and a continuation-in-part of U.S. Ser. No. 09/333,379 filed Jun. 15, 1999, (now U.S. Pat. No. 7,412,357). These applications are incorporated by reference herein in their entirety.FIELD OF THE INVENTION
The present invention relates generally to heavy-duty off-highway trucks, and more particularly to a process for designing an off-highway truck dump body.BACKGROUND OF THE INVENTION
In mining and construction environments, heavy-duty off-highway trucks are used to haul a variety of materials such as, for example, coal, rock, ore, and overburden materials. Such heavy-duty off-highway trucks generally comprise a truck chassis or frame which supports a dump body for receiving and carrying a load. In order to ensure that the dump body is properly balanced, the dump body should be designed based on an anticipated load distribution of the material carried on the truck chassis or frame. More specifically, the truck chassis anticipates a particular optimal location on the chassis where the center of gravity of the load carried in the dump body should be positioned.
Trucks with dump bodies which are often sold by the original equipment manufacturers have dump bodies designed around an assumed load configuration or load profile. In designing these dump bodies, however, the load profile which is used to size the body is based on a theoretical material angle of repose or load heap of the material irrespective of material cohesiveness, individual material heaping characteristics or material gradation. For example, in designing a dump body for hauling coal one theoretical material heap which is often used is a 3:1 heap (corresponding to an angle of repose of approximately 18°). With bodies designed to haul overburden, a theoretical material heap of 2:1 (or a different S.A.E. 2:1 heap) is often assumed.
Historically, off-highway truck manufacturers have been unable to reach a consensus with regards to the theoretical load heaps or configurations, let alone any consensus on the individual hauled material characteristics that should be used to design the dump bodies. As evidenced by their commercially available literature, some off-highway truck manufacturers use theoretical material heap profiles based on standards promulgated by the Society of Automotive Engineers (S.A.E. J 1363 January 1985) while others use their own heap profiles. Moreover, many off-highway truck manufacturers have over time alternated between using various different theoretical load heap profiles or configurations to design their dump bodies.
Off-highway truck manufacturers use these theoretical load heap profiles so that they are able to mass produce their dump bodies. However, the theoretical load heap, and the resulting theoretical load profiles, which the truck manufacturers use to design their dump bodies ignore a number of factors. For example, theoretical load profiles do not take into account the particular material characteristics of the material being loaded and hauled. In addition, theoretical load profiles do not take into account the corner voids which occur when a load is placed in the dump body. In particular, since the material is loaded from overhead into the dump body, the material tends to try to form a generally conical shape in the dump body. Because the load conforms to a generally conical shape, voids are created in the corners of the dump body where no material is present. The theoretical load profiles as used by truck manufacturers ignore these corner voids.
Additionally, field loading/haulage conditions impact the actual angles of repose that the loaded material forms in the dump body. In the loading process, material on its own flows to a natural angle of repose, however, in the loading process as the loading equipment pushes/pulls and rests on the material being loaded an imposed material angle of repose results. For instance, the method by which the material is actually loaded into the dump body, e.g. using a front-end loader or a shovel, can impact the ultimate actual profile of the load in the body. Other material characteristics such as the cohesiveness, gradation, size and consistency of the material (e.g., ore, overburden, clay, etc.) also impacts the actual load profile. Accordingly, because of differences in the materials and field loading and haulage conditions, the actual load profile or configuration of given materials in the dump body at different sites can vary extensively.
As a result, the mass-produced dump bodies supplied by off-highway truck manufacturers which are based on a theoretical material load profile are often improperly matched for a particular material haulage application. For example, the dump body may be inadvertently designed such that the dump body size and resultant load is either undersized/underloaded or oversized/overloaded and that the corresponding center of gravity of the actual load is significantly offset from where it should be placed, based on the design of the truck chassis. This causes incorrect truck loading and improper truck utilization with uneven loading of the truck chassis leading to uneven or offset frame loading, which can potentially result in truck chassis problems including uneven tire wear which often requires premature replacement of the tires; and potentially poor vehicle operating stability. As will be appreciated, since the trucks themselves and the tires used on these types of off-highway trucks are extremely costly, potential truck chassis repair and premature replacement of tires significantly increases the operating expenses associated with material haulage.
Likewise, depending on how the actual material and material heap varies from a theoretical material load profile, the dump body can be either too large or too small resulting in the truck chassis carrying loads which are both improperly placed on the truck frame and significantly heavier or lighter than intended. An improperly designed body which is too small to carry the intended load can lead to spillage of the load over the sides and off the rear end of the body resulting in significant under utilization of the truck. If side/rear spillage occurs during transport, it can result in tire damage and tire ruptures particularly on the following trucks. While too large of a body for the intended load can result in extreme truck overloads or if the load is limited to the correct load amount in the dump body, the load may often be improperly placed in the dump body leading to poor truck stability and individual truck chassis component overloads.OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, in view of the foregoing, a general object of the invention is to provide a dump body which is designed for specific field operating environments.
A related object is to provide a method for designing off-highway dump bodies which more accurately takes into account actual field conditions.
A more specific object is to provide a process for three-dimensional modeling of required dump body loads and the related design of dump bodies based on actual field conditions at particular sites.
These and other features and advantages of the invention will be more readily apparent upon reading the following description of a preferred exemplary embodiment of the invention and upon reference to the accompanying drawings wherein:
While the invention will be described and disclosed in connection with certain preferred embodiments and procedures, it is not intended to limit the invention to those specific embodiments. Rather it is intended to cover all such alternative embodiments and modifications as fall within the spirit and scope of the invention.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now more particularly to the drawings there is shown in
In the illustrated embodiment, the truck 12 is generally symmetrical about its longitudinal axis. Accordingly, as will be appreciated, many of the elements identified in the side views of
In accordance with an important aspect of the present invention, the dump body 10 is designed so that the volumetric capacity of the dump body matches the truck hauling capacity and that loads in the dump body have a center of gravity that best matches the intended load center of gravity/corresponding load distribution contemplated by the design of the truck chassis 14. More specifically, the dump body 10 is shaped and dimensioned to accommodate the correct volumetric load as well as to maintain a load distribution that results in the center of gravity of the load being proximate a predetermined location, in this case, the preferred position for the load center of gravity based on the truck manufacturer's designed chassis loading/weight distribution. Unlike previous dump body design methods, the dump body design of the present invention is not based on an assumed theoretical or universal load profile/load material heap. Instead, the present invention utilizes a load profile that is based on a detailed analysis of the actual material characteristics and loading conditions present in specific field haulage environments thereby taking into account factors such as the cohesiveness of the material to be hauled and the size, shape and gradation of the pieces of material.
For example, U.S. Pat. No. 5,887,914 issued to LeRoy G. Hagenbuch on Mar. 30, 1999 discloses a dump body design process which can be used to produce a dump body that is capable of hauling both overburden and coal. This design process assumes a theoretical 2:1 heap for overburden and a theoretical 3:1 heap for coal. It has been found that these theoretical load profile assumptions do not always provide an accurate body design of the actual haulage operating conditions which are encountered at specific job sites. Such theoretical body load profiles, are used without any consideration of the actual material, loading and hauling conditions that exist at actual locations of use. Thus, in many cases the dump body can be improperly sized and designed or matched to the material to be hauled and accordingly to the truck chassis.
In order to more accurately take into account actual field conditions, the first step in the design process of the present invention is to collect field data relating to the material characteristics and load configurations currently being hauled by trucks at the site at which the dump body 10 will be used. In particular, data should be collected with regard to the actual angles of material repose, the size and shape of any plateau formed at the top of the load and loading voids that are formed by the material when it is loaded and carried in existing dump bodies. The angles of material repose are dependent upon a number of factors including the cohesiveness of the material being hauled and the size, shape and gradation of the material pieces. With respect to analyzing the angles of repose, load plateau and loading voids of the loaded material, one method by which this can be accomplished is to photograph (or videotape) from various different angles the loads 72 presently being hauled by one or more existing off-highway trucks 74 at a site (see, e.g.,
Furthermore, since the method by which material is loaded into the truck 12 can also impact the loaded material profile, it can also be useful to collect data, via photographs or otherwise, regarding truck loading techniques and the equipment used to load the dump bodies. For example, front-end loaders generally have a wide bucket relative to the dump body length and typically load material into the dump body from the side of the truck. Accordingly, when front end-loaders will be used to load the dump body, the length of the dump body can be an important factor. Likewise, cable and hydraulic shovels tend to have narrower buckets and are also used to load material into the body typically from the side of the truck. Since cable shovels typically have a door which swings toward the shovel when dumping (i.e. towards the side of the body), the width of the body may be an important factor when shovels will be used to load the dump body. Additionally, information should be collected giving an accurate material density. The types of information which can be relevant to determining the density of the load material include visual examinations of the load material, the taking of weight samples of known volumes of the load material and consultations with the end user of the proposed dump body.
In some circumstances, such as in the case of a new mine, it may not be possible or desirable to collect material and loading data from the site at which the dump body 10 will be used. In these situations, data from a similar field haulage environment should be used. As will be appreciated by those skilled in the art, a similar field haulage environment would have conditions that parallel as closely as possible the conditions which are anticipated at the new site. This could include, for example, a nearby site or mine in which the same or similar material is hauled, a site hauling similar materials and using similar hauling equipment and/or a site using similar loading equipment. Once the new mine or site is operational, the design of future dump bodies for that site can be refined as needed and as information is developed about the material and loading conditions at the site. Of course, the material and loading conditions at sites will, in most cases, evolve over time which could necessitate further analysis of these parameters prior to the design of new additional dump bodies for that site.
Once the appropriate load heap pictorial information has been collected, the information is then analyzed to determine what are the actual angles of material repose of the loaded material and the dimensions of the top plateau of the material heap. In one presently preferred embodiment, this is accomplished by blowing up at least select representative photographs of off-highway trucks with loaded material. From these blown up photographs, the size of the plateau of the heap, the angles of material repose and the corner voids of the loaded materials are then measured. In most cases, the angles of material repose that run to the front, rear and sides of the dump body will all be somewhat different namely due to the natural and imposed angles of repose occurring as a result of the loading process. Accordingly, using the photographs, values should be determined for each of these angles repose. The various values for the front, rear and side angles of repose which are measured from the photographs are compiled and averaged respectively in order to produce a composite front angle of repose, a composite rear angle of repose and a composite side angle of repose which can then be used to create a three-dimensional load profile as described in greater detail below. Of course, as will be appreciated by those skilled in the art, other methods may be used to collect and analyze the data on actual dump body field haulage conditions including, for example, actual hands-on measurements of the relevant angles of repose and corner voids.
Using the values of the empty and loaded weights of the truck 12 provided by the off-highway truck manufacturer, the ideal position along the chassis 14 for the load center of gravity is then determined. As illustrated in
As shown in
The angle of the floor line 30, the lengths of the front slope line and floor line and the line defining the height of the sidewalls are adjusted as indicated by the arrows in
Next, based upon this approximate load profile 33 (e.g., shown in
To this end, in one preferred embodiment, the transition areas between the front 42 and the sides 44, and the rear 46 and the sides 44 of the three-dimensional load model 38 are divided into a number of equal segments as shown in
Each of these planes 50 is then extended using standard geometric principles until it intersects a portion of the dump body 10 such as the floor, side walls, front slope or canopy as shown in
Once the three-dimensional modeling of the material heap is completed, including the modeling of the corner voids along with a subsequent comparison with the field gathered information, the center of gravity of the resulting three-dimensional load model 38 is then determined. This center of gravity is then compared to the center of gravity location (arrow 28) contemplated by the chassis design as shown in
In the event that the center of gravity of the three-dimensional load model 38 is not close enough to the desired location, in an iterative process a new three-dimensional profile of the heaped load is generated based on the data collected from the field loading/haulage environment. Through adjustment of the parameters of the dump body (e.g., the dump body floor angle, floor length and side height), the center of gravity of this new three-dimensional heaped load profile is moved through the iterative process until it is in close proximity to the desired location. These steps being repeated in an iterative fashion as necessary until the center of gravity of the three-dimensional load model is adjusted to be approximately coincident with the anticipated center of gravity contemplated by the design of the truck chassis 14.
The final design of the dump body 10 is shown in
As will be appreciated, the use of actual angles of repose gathered from data taken from the actual field haulage conditions in which the dump body 10 will be employed can have a significant impact on the model of the load and thus ultimately on the design of the dump body. For example, as shown in
An example of how these differences in the load model can impact the location of the center of gravity of the load as it is carried in a dump body and the rated capacity or yardage of the dump body is shown in
In view of the foregoing, it will be appreciated that, unlike the theoretical load profiling currently being done, the body and design process of the present invention takes into account the field material, loading and hauling conditions in which the dump body will be used and provides a method by which this information can be used in a meaningful manner in designing the dump body. Thus, a much more accurately designed dump body is produced resulting in improved body capacity and corresponding load retention, and proper placement of the load on the truck chassis and tires.
In accordance with a further aspect of the present invention, the floor 20 of the dump body 10 can be configured so as to help ensure that the load is placed in the proper position in the dump body 10 during the loading process. In particular, the rear edge 90 of the floor 20 of the dump body can have a rounded or curved configuration, as shown in
According to another aspect of the present invention, for situations in which a relatively large capacity cable shovel bucket will be used to load material into the dump body, the dump body 10 can be designed with a relatively wider inside body width than conventional dump bodies in order to substantially reduce the impact force of the falling load and ensure that the load is properly placed within the dump body. Specifically, as the size and capacity of the buckets on cable shovels has increased, it has become possible to fill a dump body to capacity in four or less passes with the shovel bucket. However, using such large capacity loading buckets to load dump bodies has led to loads being improperly placed within the dump body and substantial increases in the impact force caused by the material as it drops into the dump body.
As explained above, cable shovel buckets 60 (
Additionally, when loading conventional dump bodies with large capacity buckets, the clearance between the floor 104 of the dump body 100 and the swinging gate 62 in the freed position cannot be minimized because the operator must ensure that the bucket does not come into contact with the sidewalls 102 of the dump body. As a result, the load must be dropped from the bucket 60 at a relatively large distance above the floor 104 of the dump body 100. Because of the extremely large capacity of these large buckets, the dropping material produces a very substantial impact force when it contacts the floor of the dump body. This impact force significantly increases the wear on the dump body and can severely jar the operator of the truck.
In contrast to conventional loading operations involving prior art dump bodies and large capacity buckets, the present invention provides a method by which material can be loaded from a minimal height substantially into the center of a dump body 10 using a large capacity bucket 60 whose volumetric capacity is approximately ¼ or more than that of the dump body 10. As shown in FIG. 24, this is accomplished by using a relatively wider dump body 10 that has relatively lower sidewalls 16 than the similar capacity dump bodies conventionally provided by off-highway truck manufacturers. This allows a bucket operator to bring the bucket 60 into a substantially lower position in which just enough clearance is provided from the floor 20 of the dump body for operation of the swinging gate 62 before discharging the load from the bucket. In particular, using a relatively wider dump body 10, enables a shovel operator to lower the bucket 60 to a position that: (1) substantially minimizes the clearance between the floor 20 of the dump body 10 and the swinging gate 62 so as to minimize the impact force of the dropping load and (2) allows the material to be discharged substantially in the center of the dump body 10 while (3) allowing the swinging gate 62 to clear the sidewalls 16 of the dump body as it swings through an arc after it is freed. Thus, the method of the present invention results in a more balanced load on the dump body and a substantially reduced impact force from the discharge of the bucket load.
All of the references cited herein, including patents, patent applications, and publications, are hereby incorporated in their entireties by reference.
While this invention has been described with an emphasis upon preferred embodiments, it will be obvious to those of ordinary skill in the art that variations of the preferred embodiments may be used and that it is intended that the invention may be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications encompassed within the spirit and scope of the invention as defined by the following claims.
1. A process for designing an off-highway truck body of an off-highway truck, the off-highway truck including an off-highway truck chassis, the process comprising:
- developing a substantially conical-shaped volumetric model of a payload; and
- developing a design of the truck body around the volumetric model, the design of the truck body including a floor, a front wall, side walls and an open end.
2. The process recited in claim 1, wherein the volumetric model includes a volume, and wherein the volume is dependent upon a hauling capacity of the off-highway truck chassis.
3. The process recited in claim 1, wherein the volumetric model includes a plateau.
4. The process recited in claim 1, wherein the volumetric model includes a volume, and wherein a position of at least one of the floor or the front wall is adjusted so as to change the volume held by the design of the truck body.
5. The process recited in claim 1, wherein the volumetric model includes a volume, and wherein a width between the side walls is adjusted so as to change the volume held by the design of the truck body.
6. The process recited in claim 1, wherein the volumetric model includes a density.
7. The process recited in claim 1, wherein the volumetric model includes a volume, and wherein the volume is determined as a function of a payload capacity of the off-highway truck chassis divided by a density.
8. The process recited in claim 1, wherein the design of the truck body is developed in order to position the volumetric model on the off-highway truck chassis so as to provide a load distribution according to a predetermined load distribution of the off-highway truck chassis.
9. The process recited in claim 1, wherein the volumetric model incorporates an angle of repose.
10. The process recited in claim 9, wherein the angle of repose is collected from an operational site of the off-highway truck.
11. The process recited in claim 9, wherein the angle of repose is collected from a site other than an operational site of the off-highway truck.
12. The process recited in claim 9, wherein the angle of repose is collected through a consultation with a user of the off-highway truck.
13. The process recited in claim 9, wherein the angle of repose is based on characteristics of a material of the payload.
14. The process recited in claim 1, wherein the volumetric model incorporates a plurality of angles of repose.
15. The process recited in claim 14, wherein the angles of repose include a front angle of repose.
16. The process recited in claim 14, wherein the angles of repose include a rear angle of repose.
17. The process recited in claim 14, wherein the angles of repose include a side angle of repose.
18. A process for producing an off-highway truck body of an off-highway truck, the off-highway truck including an off-highway truck chassis, the process comprising:
- developing a substantially conical-shaped volumetric model of a payload; and
- developing a design of the truck body around the volumetric model, the design of the truck body including a floor, a front wall, side walls and an open end; and
- producing an off-highway truck body based on the design of the truck body.